
Class. 







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COPYRIGHT DEPOSIT. 



STEEL AND ITS TREATMENT 



STEEL 



AND ITS TREATMENT 



BY THE 

METALLURGICAL 

OF 

E. F. HOUGHTON 


STAFF 

& CO. 

& CO. 




THIRD EDITION 

ILLUSTRATED 


• ••, 

• » 


PHILADELPHIA 

E. F. HOUGHTON 
1918 








COPYRIGHT 1914 
COPYRIGHT 191 8 

BY 

E. F. HOUGHTON & CO. 



ALL RIGHTS RESERVED 



PUBLISHED 1912 
SECOND EDITION, OCTOBER 1914 
THIRD EDITION, JANUARY 1918 



HOUGHTON LINE/ PRESS 
PHILADELPHIA 

MAR 2 1918 
©CI.A481967 



' It. f 



FOREWORD TO THIRD EDITION 



THE welcome reception of our second edition 
of this book by the iron and steel working 
industries has encouraged us to greater ef- 
fort in striving to make this third edition worthy of a 
place on every steel worker's bookshelf. 

From the first chapter the book has been almost 
entirely rewritten, numerous micro-photographs and other 
illustrations have been added, and the steel specifications 
of the Society of Automotive Engineers have been cor- 
rected to date of going to press. 

Grateful acknowledgment is due Mr. L. A. Cummings, 
metallurgist of the New Departure Manufacturing Co., 
Bristol, Conn., for painstaking assistance in editorial 
work; to Mr. Howard J. Stagg, Jr., metallurgist of the 
Halcomb Steel Co., Syracuse, N. Y., for several of the 
micro-photographs reproduced herein ; to Air. Frank N. 
Sim, advertising manager of the Timken-Detroit Axle 
Co., Detroit, Mich., for photographs of the Timken Rol- 
ler Bearing Co. plant at Canton, Ohio ; to Mr. A. L. God- 
dard, Superintendent of Shops, University of Wisconsin, 
Madison, Wis., for many helpful suggestions which were 
adopted; to the Society of Automotive Engineers for per- 
mission to reproduce the steel specifications ; to the 



vi STEEL AND ITS TREATMENT 

editors of Machinery, who kindly consented to the use 
of illustrations which originally appeared in that Dup- 
lication, and to the many others who have promptly and 
liberally done their bit to aid us in our efforts. 



FOREWORD TO SECOND EDITION 



F 



OR over forty years E. F. Houghton & Co. have 
been engaged in the manufacture of products 
used in the heat treatment of steel. 



During that period they have conducted a laboratory 
of research that they might best comprehend the require- 
ments of the steel industries and thus produce the best 
products. 

This research work has been carried on by the metal- 
lurgical force of the Company, and for many years con- 
sisted mostly in absorbing the individual experience of 
each works where for the most part nothing more than 
rule of thumb methods was applied. 

During the last fifteen years with the rapid develop- 
ment in the heat treatment of steel, owing to the increased 
demand for high-service machine parts, a more careful 
and scientific study of the heat treatment of steel has 
been possible, and this little work is nothing more or less 
than the collection of such data as has been obtained 
from time to time by our metallurgical force plus the cor- 
rection of palpable errors, the reconciling of seeming 
inconsistencies and the deduction of a code of principles. 

The object of this little work is to aid the reader in a 
clearer understanding of the wonderful metal — steel — in 



viii STEEL AND ITS TREATMENT 

the hope that it will help improve the quality of output 
and the economy of operation. 

With this accomplished, all we aimed at, namely suc- 
cess, will have been attained. 



TABLE OF CONTENTS 

CHAPTER PAGE 

I Composition of Steel I 

II Thermal Critical Points of Steel 7 

III Classification of Steel 13 

IV Effect of the Elements in Steel 17 

V Annealing 30 

VI Physical Properties 36 

VII Pyrometers 47 

VIII The Thermal or Heat Treatment of Steel 51 

IX Carburizing 55 

X Case-Hardening 66 

XI. Carburizing Material 67 

m 

XII Heat Treatment After Carburizing 74. 

XIII The Hardening of Steel , 76 

XIV Drawing or Tempering 80 

XV Furnaces for Case-Hardening 82 

XVI Heating 88 

XVII Fuels 89 

XVIII Quenching 90 

XIX Miscellaneous Hardening Methods 93 



LIST OF ILLUSTRATIONS 



FIGURE PAGE 

1 Wrought Iron, Ferrite 2 

2 Steel, Ferrite and Pearlite 2 

3 Ferrite and Pearlite 3 

4 Ferrite and Pearlite 4 

5 Pearlite or Eutectoid 4 

6 Pearlite and Excess Cementite 5 

7 Austenite and Martensite 6 

8 Critical Points in Steel (chart) 8 

9 Roberts- Austin Chart 10 

I o A Martensite 11 

I oB Martensite 11 

I I Normalizing and Hardening Temperatures 15 

12 Manganese Sulphide 20 

1 3 Slag in low carbon steel 24 

1 4 Slag in low carbon steel 24 

1 5 Slag in spring steel 25 

16 Ingot of steel, grain structure 27 

1 7 Steel Ingot, rolled and hammered 27 

1 8 Steel Ingot, result of light blows 27 

1 9 Steel Ingot, annealed 27 

20 Steel Ingot, properly hardened 27 

2 1 Steel Ingot, overheated 27 

2 2 Steel Ingot, restored by hammering or heat treatment 2 7 



xii STEEL AND ITS TREATMENT 

FIGURE PAGE 

23 A Swedish Iron, grain distortion, elongated 28 

23B Swedish Iron, normal grain 28 

23C Swedish Iron, grain distortion, compressed 29 

23D Swedish Iron, bent double 29 

24 Globular Cementite 31 

2 5 Laminated Pearlite 32 

26 Slip band caused by burning 34 

27 Tensile Strength of wrought iron (chart) 38 

28 Depth of Carbon Penetration 59 

29 Depth of Carbon Penetration 59 

3 o Depth of Carbon Penetration 60 

31 Excess Carbide or Free Cementite 62 

32 Graduation of carbon from case to core 64. 

33 Coarse crystallization of case or * 'Freckled Corners" 69 

34 Surface Decarburization 70 

35 Surface Decarburization 70 

3 6 Uneven penetration of carbon 71 

3 7 Uneven penetration of carbon 71 

38 Carburizing furnaces, New Departure Mfg. Co 83 

39 Hardening furnaces, New Departure Mfg. Co. 85 

40 Heat treating furnaces, New Departure Mfg. Co. ... 86 

41 Oil quenching and cooling tanks (diagram) 91 

42 Fork for handling small carburizing boxes 97 

43 Truck for handling heavy carburizing boxes 98 

44 Packing pots at Timken Roller Bearing Co 1 00 

45 Unpotting parts at Timken Roller Bearing Co 100 



CHAPTER I 
COMPOSITION OF STEEL 

Steel is not a simple substance like pure iron, gold or 
copper, but a complex artificial product. It is composed 
of groupings of many constituents which enter into its 
makeup as granite rock is built up of the minerals quartz, 
mica and feldspar. These constituents, as they may be 
called, are only visible with the aid of the microscope. 

Upon etching a highly polished piece of steel, this gran- 
itic structure is made apparent through the action of the 
etching medium (acid or other corrosive or abrasive ma- 
terial) which affects the constituents variously, causing 
each to assume a structure peculiar to itself. 

Steel lies between wrought iron or nearly carbonless 
iron on one hand, and cast or high carbon iron on the 
other, and is practically free from slag. It differs from 
both in that it is susceptible to more marked physical and 
structural modifications than either upon the application 
or abstraction of heat. 

Iron containing less than .03 per cent, carbon is gen- 
erally called wrought or ingot iron, and contains consid- 
erable slag (Fig. 1) ; more than .03 per cent, and less 
than 1.80 per cent, carbon is called steel; while with 
a content of 1.80 per cent, carbon or over it is consid- 
ered cast iron. 

Steel is composed of pure iron or ferrite and iron car- 
bide (Fe3C, containing 6.6 per cent, carbon, 93.4 per cent, 
iron), together with certain impurities in solid solution. 
The Ferrite of commercial grades of iron and steel is not 
pure iron, but rather a solid solution of iron holding 
small amounts of silicon, phosphorus and other impurities. 
2 



STEEL AND ITS TREATMENT 




Wrought Iron. White Areas, Ferrite. Dark Patches, Slag. 
Magnification, 75 Diameters. 




Fig. 2. 

Steel. White Areas, Ferrite. Dark Areas, Pearlite. 
Magnification, 100 Diameters. 



COMPOSITION OF STEEL 3 

A certain fixed amount of carbide will dissolve in iron 
and when that fixed amount is exceeded, there will be a 
precipitate of free carbide called "Cementite." The point 
of complete saturation of Ferrite with Cementite is reached 
at .85 to .90 per cent, carbon ; in plain carbon steels, and 





Steel. White Areas, Ferrite. Dark Areas, Pearlite. 
Magnification, 1000 Diameters. 

in the soft and annealed condition the microscopic struc- 
ture shows neither Ferrite nor Cementite but a mechan- 
ical mixture called "Eutectoid" or "Pearlite." (Fig. 5.) 

The behavior of iron upon the addition of carbon is 
about as follows : 

At first we have pure iron or Ferrite, then as we add 
a little carbon which with the Ferrite forms Cementite, 
the result is not free Cementite but a mixture of Pearlite 
(which is in turn a mechanical mixture of Cementite and 
Ferrite, but always in a certain fixed proportion) and 
Ferrite (Figs. 2, 3 and 4.) As the carbon increases 
the amount of Pearlite increases until all the Ferrite has 
been used up in its formation, and the steel consists en- 
tirely of Pearlite (Fig. 5). This occurs at .85 to .95 per 



STEEL AN'D ITS TREATMENT 




Fig. 4. 

White Areas, Ferrite. Dark Areas, Pearlite. 
Magnification, 150 Diameters. 




Fig. 5. 
Pearlite or "Eutectoid." Magnification, 1000 Diameters. 



COMPOSITION OF STEEL 



cent, carbon, and when the carbon content exceeds this 
amount, we begin to get excess Cementite (Fig. 6) ; the 
formation of excess Cementite up to 6.6 per cent, carbon 
giving a structure composed entirely of Cementite, if such 
an alloy was commercially available, as cast iron or steel. 




Fig. 6. 
Dark Areas, Pearlite. White Lines, Excess Cementite. 

The carbon content of a steel may be estimated by the 
relative percentage of each constituent present as shown 
under the microscope, as .90 carbon steel will show all 
Pearlite ; .45 carbon steel half Ferrite and half Pearlite, 
and 1.50 carbon steel 90 per cent. Pearlite, 10 per cent. 
Cementite. 

Like most substances, these combinations of constitu- 
ents are decomposed by the action of heat, new ones being 
formed. Water at 60 degrees Fahr. is a liquid. It is 
likewise a liquid at 211 degrees Fahr., but at 212 degrees 
Fahr. it becomes vapor or steam. So the elements Fer- 
rite and Pearlite in hypoeutectoid steel or Pearlite and 
Cementite in hypereutectoid steels remain at such up to a 
temperature of 700 C. (1292 Fahr.) to 845 ° C. (1553 



6 STEEL AND ITS TREATMENT 

Fahr.), depending upon the quantity of each present, 
when they decompose through several transitional stages, 
forming a new constituent known as "Austenite," as 
shown in Fig. 7, or Austenite and Cementite in case 
of hypereutectoid steels. 




Fig. 7. 

Austenite and Martensite (Osmond). 
Reduced one-half from original cf 1000 Diameters. 

Now this Austentite differs materially in its properties 
from either Ferrite or Pearlite, in that, if it or more 
usually one of its transitional forms, Martensite, be pre- 
served by quenching the steel, it will be found hard and 
brittle, while Ferrite and Pearlite are soft and tough. 
Again Ferrite and Pearlite attract the magnet under all 
conditions, while the new constituent, Austenite, in its hot 
condition does not; but in its cold condition it acts the 
same as Ferrite and Pearlite. 

On account of the close relation existing between the 
treatment and structure of steel, and the structure and 
physical properties, one realizes the importance of gain- 
ing a knowledge of what is called the critical points in 
steel, in order to lay the foundation for its heat treat- 
ment. 



CHAPTER II 

THERMAL CRITICAL POINTS OF STEEL 

If one should watch the slow heating of a piece of steel 
in a furnace, it would be noted that the temperature of 
the steel gradually increases with the increasing heat of 
the furnace until a temperature is reached when the steel 
may become slightly darker and cooler than the furnace. 
As the heating is continued the piece will again assume 
the temperature of the furnace. 

In the rising heat the darkening of the piece of steel 
is due to the absorption of heat to convert Ferrite and 
Pearlite into Austenite. 

Now if the furnace be permitted to cool slowly, during 
some point in the process the steel may become brighter 
or visibly hotter than the furnace, after which it assumes 
its normal rate of cooling which continues on down to 
atmospheric temperatures. 

Such a rise in temperature in slow cooling indicates a 
giving off of heat during the conversion of the Austenite 
back to Ferrite and Pearlite. 

Fig. 8, taken from Machinery, July, 1912, shows clearly 
this loss and gain of heat at the points Ac and Ar. 

A transformation of the constituents composing the 
steel accompanies these thermal changes — as, for example, 
on heating, the decomposition of Ferrite and Pearlite to 
form Austenite, as mentioned above, or vice versa, the 
decomposition of the Austenite into its constituents, Fer- 
rite and Pearlite, as the case may be, during slow cooling. 

The temperatures or points where these changes take 
place during the heating and cooling are called the crit- 
ical points of steel. To distinguish between these two 



STEEL AND ITS TREATMENT 



1500 

1400 

1300 

ft 1200 
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a 
5 1100 

UJ 
CC 

Siooo 

900 

800 
700 










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Fig. 8. 



THERMAL CRITICAL POINTS OF STEEL 9 

points, or ranges as is actually the case, those occurring 
pn the heating are termed "Decalescence" and those on 
the cooling "Recalescence" points. 

j i These terms are usually noted by the symbols Ac for 
Decalescence and Ar for Recalescence. The sub num- 
erals attached as in Chart, Fig 9, refer to other criti- 
cal temperatures at which other structural changes take 
place under similar conditions. 

When the various critical points occurring in steel are 
considered collectively, the range of temperature that 
they cover is called the critical range. The critical range 
! may include one, two or three points. The meaning of 
the expressions "Critical Range on Heating" and "Criti- 
Cal Range on Cooling" is obvious. 

The carbon percentage influences the location of the 
thermal points as shown in Roberts-Austen Chart, Fig. 9. 

These ranges have a value which is of great importance 
in practical work. 

Without a lengthy discussion of the theoretical points 
of the Roberts-Austen Chart, Fig. 9, we will con- 
sider steels under heat conditions of various carbon con- 
tents. Take for instance, a steel containing less than .37 
per cent, carbon, as it passes through Aci, the initial 
Pearlite begins to change to Austenite, the solid solution, 
and then begins to absorb the free Ferrite until at Ac3 
the original steel is entirely composed of Austenite. On 
slow cooling the reverse is true. The conversion tem- 
peratures being lowered, as shown at Ar3, Ar2 and An. 
However, when quenching at a temperature correspond- 
ing to A, above Ac3, we do not retain Austenite but 
Martensite. It is impossible to obtain Austenite in com- 
mercial work, as the quenching is not sufficiently rapid 
to retain this condition. Martensite (Figs. 10a and 10b) 
is harder and somewhat more brittle than Austenite. 
If, however, we quench at a point corresponding to tem- 
perature C, we retain Ferrite and Pearlite or Sorbite. 

Considering, next, a steel of carbon content, between .37 
and eutectoid, we have, on heating, only two critical tern- 



10 



STEEL AND ITS TREATMENT 




THERMAL CRITICAL POINTS OF STEEL 11 




Fig. 10a. 

Marten site. Magnification, 375 Diameters. 




Fig. 10b. 
Martensite. Magnification, 10C0 Diameters. 



12 STEEL AND ITS TREATMENT 

peratures, Aci and AC32. In this case the initial Pearlite 
is greater than Ferrite and the transformation to Austen- 
ite and the absorption of Ferrite are more rapid. 

For a Eutectoid Steel, .85 to .90 per cent. Carbon, all 
the critical temperatures on heating are merged into a 
common AC321. There being no free Ferrite, but only 
Pearlite present, the transformation takes place rapidly 
and at one time. 

Hypereutectoid Steel consists of Pearlite and Free Ce- 
mentite. On heating through AC321 the Pearlite is 
changed to Austenite. If we heat past the upper critical 
point Accm the Austenite dissolves the free Cementite 
and the steel becomes entirely Austenitic. It will not be 
necessary, in ordinary commercial treatments, to consider 
the Accm critical temperature. If steel is quenched from 
a temperature corresponding to B, in Fig. 9, in ice water, 
the Austenite can then be retained. If steel is quenched 
at a temperature corresponding to D, in the chart, the 
structure retained will be Cementite and Martensite. 

The decalescent and corresponding recalescent points 
do not occur at exactly the same temperature, the de- 
calescent points generally occurring some 25 ° C. (/7° 
Fahr.) to 50 C. (122 Fahr.) higher than the recalescent. 
For instance, in Fig. 8, you will note the point Ac is 
shown at 750 C. (1382 Fahr.), while the correspond- 
ing Ar point is 690 ° C. (1274 Fahr.). 

It does not follow, however, that these two points are 
not the opposite phases of the same phenomena. The 
fact that the critical point on cooling lags behind the 
point on heating, and vice-versa, is evidently a case of 
hysteresis, so often observed in physical phenomena, im- 
plying a resistance of certain bodies to undergo a trans- 
formation, when theoretically the transformation is due. 

The slower the process of heating and cooling, the 
nearer will the two points approach each other, so that 
with infinitely slow cooling and heating they would un- 
doubtedly occur at exactly the same temperature. 



CLASSIFICATION OF STEEL 13 



CHAPTER III 
CLASSIFICATION OF STEEL 

Steels are commonly divided in two classes — straight 
carbon steels and special steels, or alloy steel. The former 
differ from the latter in that they are made up almost 
entirely of iron combined with more or less carbon and 
containing small amounts of such elements as manganese, 
sulphur, phosphorus, silicon, while the special steels re- 
sult from alloying the above with nickel, chromium and 
vanadium and other elements. 

Straight Carbon Steels 

Steels are generally graded according to the amount of 
carbon they contain. The following terms are those most 
commonly used : 

Very low carbon steel, very mild or extra mild steel; 

Very soft, dead soft steel — carbon not over .10 per 
cent. ; 

Low carbon steel, mild steel, soft steel — carbon not 
over .25 per cent. ; 

Medium carbon steel, high carbon machinery steel — 
carbon .26 to .60 per cent. 

High carbon steel, tool steel — carbon over .60 per 
cent. ; 

Extra high carbon steel, high carbon tool steel — carbon 
over 1.25 per cent. 

This classification is somewhat arbitrary, as there are 
no sharp lines in the carbon percentages of separation 
universally recognized between the various grades. 

Steel containing .85 to .90 per cent, carbon is also 
known as "Eutectoid" steel, that containing less than 



14 STEEL AND ITS TREATMENT 

.85 per cent, carbon as "hypoeutectoid" steel, and more 
than .90 per cent, carbon metal as "hypereutectoid" steel. 

Low Carbon Steels 

If one should study the rate of cooling of a sample of 
steel containing some .10 per cent, carbon, from a high 
temperature, three thermal retardations would be de- 
tected: Ar3, at about 850 C. (1562 Fahr.) ; Ar2 near 
760 ° C. (1400 Fahr.), and An about 700 C. (1292 
Fahr.). Of these three critical points the Ar3 would be 
the most marked, while Ar2 and An would be faint. 
On heating, corresponding retardations will occur, due 
to spontaneous absorption of heat, the critical points be- 
ing designated as AC3, Ac2 and Aci. Of these, Ac3 and 
Aci will occur at temperatures some 25 ° C. or more 
higher than Ar3 and An, while Ac2 will be nearly the 
same as Ar2 — that is, about 760 C. (1400 Fahr.). 

The point A2 is generally less marked than the points 
A3 and Ai, and unlike A3, its position is little affected 
by the carbon content; and unlike A3 and Ai, the point 
on heating Ac2 occurs at nearly the same temperature as 
the point on cooling Ar2. 



Thermal Critical Points of a Medium Carbon Steel 

The cooling of a steel containing about .45 per cent. 
carbon reveals the existence of two critical points : One, 
evidently the point of recalescence, An, at the usual 
temperature, 700 C. (1292 Fahr.), and one upper point 
around 740 C. (1364 Fahr.). It is generally assumed 
that the two upper points have united to form a single 
one, and is designated accordingly by Ar3, 2. Increasing 
the carbon content decreased the interval of temperature 
between the two upper points, until finally for a certain 
carbon content the points meet to form the double point 



CLASSIFICATION OF STEEL 



15 



Ar3, 2. This appears to occur in commercial steels at 
about .30 per cent, carbon. 

High Carbon Stkexs 

Eutectoid steel (.85 to .90 per cent, carbon) shows a 
single very marked critical point on cooling at 700 C. 




.4 5 .6 

Carbon 

Fig. 11. 

Normalizing or Heat Treating and Hardening Temperatures for Plain 

Carbon Steels. 

(1292 Fahr.) which is designated by the symbol Ar32i, 
the three points having merged. In hypereutectoid steels, 
there is an upper critical point Acm, which corresponds 
to the point where the excess Cementite is absorbed or 
rejected by the Austenite (which has transformed from 



16 STEEL AND ITS TREATMENT 

the Pearlite) as the case may be. This point varies from 
700 ° C. (1292 Fahr.) to iooo C. (1832 Fahr.) as the 
carbon content ranges from .85 to 2.00 per cent. 

In order to put rolled or forged steel into the best 
and most uniform condition for subsequent treatments 
(hardening and tempering) it is often normalized. Nor- 
malizing consists of heating steel to certain definite tem- 
peratures well above all critical points and cooling at the 
proper rate to below redness. Properties of the steels 
of course will vary according to temperatures and rate 
of cooling. High carbon steels must be treated above 
the Ac.cm range to break up net work and large crystals 
of Cementite. The accompanying curves show suitable 
normalizing or heat treating temperatures and the hard- 
ening temperatures for plain carbon steels. 



CHAPTER JV 
EFFECT OF THE ELEMENTS IN STEEL 

The elements that combine to make steel, their relation 
to one another, the effect when the percentages' of two 
or more are changed, which add or take away certain 
physical properties of the steel, and their action upon 
heating and cooling, offer a field that cannot be covered 
in this treatise. However, it may be well to give the 
general characteristics of these elements as they manifest 
themselves in the heat treatment and establish a relation 
between the chemical analysis of steel and its effect on 
the final product. 

Carbon 

The general influence of carbon in steel is to give 
greater tenacity. It also renders the steel susceptible to 
heat treatment. The tensile strength is increased about 
three to four tons per square inch for each additional .10 
per cent, carbon, while the ductility is decreased about 5 
per cent, for each additional .10 per cent, carbon. Steel, 
with .20 per cent, carbon, begins to show appreciable 
hardening when cooled quickly, but does not show evi- 
dence of brittleness in the normal state until the carbon 
has reached approximately .70 per cent. For the most 
part, the tables and treatments, together with the physical 
properties that are mentioned later on, are the best in- 
dications of the properties of carbon and its relation to 
steel and the other elements. 

Manganese 

Manganese is an element always found in steels, but its 
true properties and effects were not known until about 
3 



18 STEEL AND ITS TREATMENT 

twenty years ago, when they were discovered by R. A. 
Hadfield, a metallurgist and steelmaker of Sheffield, 
England. 

When more than 2 per cent, and less than 6 per cent, 
of manganese is added, with the carbon less than 0.5 per 
cent, it makes the steel very brittle. 

From 6 per cent, of manganese up this brittleness 
gradually disappears until 12 per cent, is reached, when 
the former strength returns and reaches its maximum 
at about 14 per cent. After this a decrease in toughness, 
but not in transverse strength, takes place until 20 per 
cent, is reached, after which a rapid decrease again 
occurs. 

Steel with from 12 to 15 per cent, of manganese and 
about 1.25 per cent, of carbon is very hard and cannot 
be machined or drilled in the ordinary way; yet it is so 
tough that it can be twisted and bent into peculiar shapes 
without breaking. 

Manganese in the form of a ferro compound contain- 
ing about 80 per cent, of manganese, is added to steel 
at the time of tapping, so that the manganese may absorb 
the oxygen, which is dissolved in the bath, and transfer 
it to the slag as oxide of manganese. Manganese pre- 
vents the coarse crystallization which the sulphur and 
other impurities would otherwise induce, and steels low 
in phosphorus and sulphur require less manganese than 
those having comparatively high percentages. 

The maximum temperature to which it is safe to heat 
steel, both in its manufacture and subsequent treatment, 
is raised by manganese, owing to its resisting the separa- 
tion of the crystals in cooling and conferring the quality 
of hot ductility. This makes it one of the most valuable 
factors in the making of steel if the proper percentages 
are used. 

Phosphorus 

The impurities, phosphorus and sulphur, have been the 
bane of engineers, designers and all users of steel prod- 



EFFECT OF THE ELEMENTS IN STEEL 19 

ucts, and more time, more energy and more money have 
been spent to get rid of phosphorus than any other ele- 
ment in steel. It was formerly thought that phosphorus 
up to about .12 per cent, strengthened steel, but when 
these same steels were put into- actual use they failed and 
the cause was nearly always traced to the phosphorus. 
In the rolling mill, phosphorus does not show any bad 
effects, as the heat under which the steel is worked seems 
to overcome them, but when the metal has cooled and is 
subjected to sudden shock or to vibrational stresses it 
breaks very easily. The lower the temperature and the 
higher the phosphorus the more brittle the steel. This 
had led to the term "cold shortness," being applied to the 
effect of phosphorus in steel. 

Phosphorus reduces the ductility of steel under a grad- 
ually applied load, as shown by the reduction of area, 
elongation and elastic ratio when specimens are pulled 
in the ordinary, static strength-testing machine. But 
when the steel is tested in the rotary or alternating vi- 
brational-stressing machine, as well as with a pendulum- 
impact machine, the decrease in ductility and toughness 
is shown to a much greater degree. 

High phosphorus steels (over jio per cent.) are coarse 
grained and may show a reasonably high static ductility 
and still show brittleness when shock tests are applied. 

Therefore, for all steels subjected to strains, or sudden 
shocks, the phosphorus content should be below .045 per 
cent. 

Sulphur 

Sulphur causes steel to crack and check in rolling, 
forging, heat-treating or hot working, and therefore the 
term of "hot shortness" has been applied to its effect on 
steel. 

Since manganese has a great affinity for sulphur these 
two elements, when brought together at the high tem- 
perature in the manufacture of steel, combine chemically, 



20 STEEL AND ITS TREATMENT 

forming manganese sulphide (Fig. 12), which segre- 
gates and collects between the crystals of the steel and 
if present in large quantities causes an injurious effect 
by reducing the crystalline cohesion. Red shortness is 
probably caused by the melting of manganese sulphide 
(which has a lower melting point than steel) during hot 




Fig. 12. 

Dark Areas, Manganese Sulphide. 

Reduced one-half from original Diameter of 50. 

working which destroys the cohesion between the grains 
of the metal and produces cracks. Hence, the percentage 
of sulphur in steel should be extremely low. It is cus- 
tomary to specify steel containing less than .05 per cent, 
sulphur. 

Phosphorous and sulphur up to .12 per cent, are often 
added to give machining properties, but this gives a poor 
quality steel. 

Silicon 

Silicon has a tendency to remove the gases and oxide 
from steel as well as the traces of dissolved oxygen. This 
prevents the formation of blow holes and gives the steel 
greater soundness and toughness. Thus it is better able 
to withstand wear or crushing from continual pounding. 

The influence of silicon, on the results of quenching, 
is similar to that of carbon in many ways. It is also 
dependant upon the co-existing amount of carbon and 



EFFECT OF THE ELEMENTS IN STEEL 21 

manganese. It neutralizes the injurious tendencies of 
manganese. 

Nickex 

Nickel in steel increases its strength, ductility, tough- 
ness, resistance to abrasion and shock. It also increases 
very considerably the ratio of the elastic limit to the tensile 
strength, and renders these steels more susceptible to heat 
treatment. 

Steels contain from .50 per cent, to 5 per cent, of nickel, 
according to the desired results. 

An addition of 2 per cent, nickel to a steel, when 
properly treated, will increase its strength to nearly double 
that of straight carbon steel of the same carbon content. 

Nickel added to ordinary carburizing steel in com- 
paratively small percentages obviates the brittleness of the 
core which is usually produced by carburizing and gives 
more uniform results. 

These steels, when properly carburized and heat treated, 
give excellent service in such parts as shafts, ball and 
roller bearings, gears, etc. 

It should be remembered, however, that the mere ad- 
dition of nickel to steel does not guarantee exceptional 
physical properties, which can only be obtained by the 
most careful heat treatment. 

In recent years considerable work has been done on 
the higher nickel steels which give a Martensitic structure 
on air cooling. These experiments have been conducted 
on high carbon, high nickel steels, as well as low carbon, 
high nickel steels carburized. The theory of this process 
is based on the retaining, by the presence of the high 
nickel content, of the Martensitic structure on slow cool- 
ing, thereby eliminating the quenching operation. It 
should be remembered that the Martensitic structure of 
ordinary high carbon steel can only be retained by rapid 
cooling, such as quenching. 

The critical temperatures are lowered by the addition 
of nickel. In commercial steels (under 7 per cent, nickel) 



22 STEEL AND ITS TREATMENT 

for each one per cent, of nickel Ac will be lowered 15° 
Fahr. (8° C.) to 20 Fahr. (n° C), and Ar 30 Fahr. 
(17 C.) to 40 Fahr. (22 C), below the same ranges 
for straight carbon steels of the same carbon content. 

Chromium 

Chromium added to steel increases the elastic limit, 
hardness, resistance to shock and alternate stresses. 

It is the most active element in making steel respond 
to heat treatment, giving the greatest hardening depth 
obtainable with any steel. 

This element decreases the tendency of crystalline 
growth and imparts a very fine dense grain structure. 

In the rolled or forged condition low chromium, in 
combination with low carbon, has practically no effect 
on the physical properties, but it affects materially the 
results obtained by heat treating the same. 

Extreme hardness may be obtained in chromium steels, 
as the chromium intensifies the sensitiveness of the metal 
to quenching and greatly reduces the liability to fracture, 
which is found in carbon steels. 

Chromium steel practically shows extremely fine grain 
and possesses a high power of resistance to shocks. This 
has made it almost universally used for armor plate. 

When chromium is combined with nickel or vanadium 
it makes the strongest and best wearing commercial steel, 
and can be machined much more easily than when 
chromium alone is used. Small gears can be made with 
these alloying materials added to the steel so that if prop- 
erly heat treated they will be so tough and strong as to 
make it almost impossible to break out a tooth, even with 
a hammer. Some of the best grades of chrome nickel or 
chrome vanadium steel contain from .75 to 1.50 per cent, 
of chromium. Chromium renders the steel more homo- 
geneous and gives it the ability to resist shock and tor- 
sional stresses. Thus, this alloy is one of the best steels 
for crank shafts of internal-combustion engines or other 



EFFECT OF THE ELEMENTS IN STEEL 23 

parts of machinery which have to withstand similar vi- 
brational stresses. 

The chrome nickel steels are difficult to forge, as it is 
dangerous to hammer them after the temperature has 
dropped below that which makes the metal a bright yel- 
low. It must be heated repeatedly to forge pieces of any 
size or intricate shape. 

Vanadium 

Vanadium has made great strides in the past few years 
as an alloying element, and is used in steel castings and 
cast iron as well as in steel mill products. 

Vanadium, when added to steel in percentages up to 
.2 per cent., has a marked effect upon the physical prop- 
erties, particularly decreasing the susceptibility to sudden 
shock stresses and fatigue. 

Owing to its affinity for oxygen it acts as a cleanser 
to the metal, thereby increasing the molecular cohesion. 

Vanadium also removes nitrogen, which is very detri- 
mental to steel, even in infinitesimal quantities. 

Vanadium steel is used largely for crank shafts, con- 
necting rods, piston rods, crank pins, gears, saws, gun 
barrels, springs, etc. 

Impurities in Steel 

Impurities in steel usually show up when casting the 
ingot. These impurities are in the forms of segregation 
of elements, blow holes, slag, etc. The top of the ingot is 
usually in the poorest condition. Cutting off the top, 
called "cropping," if sufficiently done, removes this trouble. 
However, in the process of pouring the molten steel into 
the mold the outside becomes chilled before the core ; 
this, besides tending to trap slag, etc., exerts' a pulling 
effect on the core, causing piping and blow holes. In 
the case of high carbon steels cracks are liable to develop. 
Due to the lower heats at which high carbon steels must be 



24 



STEEL AND ITS TREATMENT 



hot worked, these cracks seldom weld up, causing trouble 
all the way through the finished product. A recently de- 
veloped method of pouring the ingot, called "box pour- 
ing," promises to give a sounder ingot. 




Fig. 13. 
Large slag inclusion in low carbon steel. 




Fig. 14. 

Large crystals of Ferrite and enclosed slag in low carbon steel. 
Reduced one-half from original of 1000 Diameters. 



EFFECT OF THE ELEMENTS IN STEEL 



25 



Below are a few micro-photographs, Figs. 13, 14, 15, 
which show some of the common impurities which cause 
considerable trouble when found in steel. 

Mechanical Treatment oe Steel 

The principal purpose of working steel is to shape it 
into the desired form. Its structure and physical prop- 
erties are dependent on the care in working and the heats 
used. The mechanical working, aside from machining, is 




Fig. 15. 
Spring steel showing slag. 

classed under two heads, namely, "Hot" and "Cold" 
Working. 

The finest grain size obtainable is undoubtedly that 
existing just as the steel has passed through the critical 
range on a rising heat. Hence, starting out with steel 
just below its solidification on undisturbed cooling the 
grain size increases until the cooling has passed through 
the critical range, and the grain size, at this stage, will 
be the resultant size at the cold temperature. Taking the 
same piece of steel, for instance, having a coarse struct- 



26 STEEL AND ITS TREATMENT 

ure, on heating there will be no change in grain size 
until the critical range is reached ; there the coarse crystals 
break up and at the upper critical point form the finest 
possible structure. Continued heating, however, above 
this point will again coarsen the grain. 

As we have stated, undisturbed cooling is a condition 
necessary for crystal growth, a coarsely crystalline struct- 
ure, however, can be partly prevented or broken up by 
vigorous hammering. If this hammering ceases above 
the critical range, coarse crystallization again sets in, and 
the higher, the temperature above the critical point at 
which the work stops, the coarser the structure will be. 
The finishing temperature in working, then, should be 
for the best results at or just above the critical range. 

The question then arises, Why not continue working 
the steel until it is cold? This would be a detriment, in- 
asmuch as the grain structure is formed in the critical 
range and "cold working" below critical range causes 
distortions and strains to set up in the grain which result 
in decreased ductility and even brittleness. This effect 
is more pronounced the lower the temperature below the 
critical point at which the steel is worked. Mechanical 
working above the critical range provides a means to 
shape steel to form by forging, refines the grain size and 
tends to impart decidedly more density than the steel 
possessed originally when rolled at the mill 

High-grade steels are hammered at the mills into bars 
and rolled to proper size. 

It will be seen from the following illustrations what 
is meant by mechanical working and the effect it has on 
the grain structure. 

It is, of course, difficult to show this effect by means 
of micro-photograph, so the pen is resorted to as a 
means of explaining the points more clearly. 

Fig. 1 6 shows the grain of steel in the ingot, for- 
getting for the time the possible conditions entering in 
steel in this form, such as segregations, pipes, etc. The 
illustration is just a cross section, before working, of a low 



EFFECT OF THE ELEMENTS IN STEEL 



27 



carbon forging steel. The subsequent illustrations are 
self-explanatory, namely, Fig. 17 shows the ingot rolled 
or hammered, and the reduction in size of grain is seen. 



Fig. 16. 
Ingot of Steel. 




Sfftf 



Fig. 17. 
Rolled and hammered. 



Fig. 18. 

Light blows. 





Annealed. 



Fig. 20. 
Properly hardened. 




Fig. 21. 
Overheated. 




Fig. 22. 



Restored by hammer- 
ing or heat treatment. 



Effect of mechanical working on grain structure. 



28 



STEEL AND ITS TREATMENT 



Fig. 18 shows the effect of improper working, the result 
of light blows on the surface, which do not extend their 




Fig. 23a. 
Elongated Crystals. 

reducing force to the center ; but this is remedied by 
annealing (Fig. 19), which promotes the adjustment of 





Fig. 23b. 
No distortion of Crystals. 



the grains and relieves the strains in working. The steel 
is now in a condition to be properly hardened, and a fine, 
even, silky grain is the result if the proper temperature 
and bath have been used in hardening (Fig. 20). If no 



EFFECT OF THE ELEMENTS IN STEEL 



29 



high temperature is used in hardening a coarsely crystal- 
line formation appears (Fig. 21), which can only be re- 




Fig. 23c. 
Compressed Crystals. 



— A 



Fig. 23d. 

Low carbon Swedish Iron bent double on itself, showing location of 

sections illustrated in Figs. 23A, 23B and 23C. 



stored, provided the piece permits, by working or ham- 
mering and proper heat treatment afterward (Fig. 22). 
A simple example of cold working is plainly shown in 
the three micro-photographs 23A, 23B, 23C. This shows 
the grain distortion at points A, B, C of a piece of low 
carbon Swedish iron when bent double on itself, Fig. 
23D. 



CHAPTER V 

ANNEALING 

Inasmuch as the annealing process has an important 
bearing upon its physical properties, its mechanical treat- 
ment and its subsequent effect on the heat treatment of 
steel after machining, it is essential that the basic prin- 
ciples of this operation be thoroughly understood. 

The purpose of annealing steel is, first, tx> increase its 
softness and ductility and facilitate subsequent machin- 
ing operations ; second, to remove existing coarseness of 
grain and secure a desirable combination of strength, 
elasticity and ductility for the resisting of strains; and, 
third, to relieve internal stresses, such as are induced by 
forging, rolling, machining, or by non-uniform contrac- 
tion in cooling. 

These changes of physical properties are due to the 
changes of structure caused by the heating operation, 
which operation consists essentially of three parts : First, 
heating the steel to the desired temperature ; second, hold- 
ing at the temperature until the steel is thoroughly heated ; 
third, cooling. 

Since all crystallization is changed in heating steel 
through the critical range, it is necessary, then, to heat the 
steel through this range as the first step in the annealing 
operation. Heating to a temperature below the critical 
range will induce no structural change whatever, but 
heating considerably above the range will again bring 
about a form of coarse crystallization, which is detri- 
mental. 

For the relief of strains, only, it would be necessary 
simply to anneal at the lowest possible temperature, — for 



ANNEALING 



31 



instance, at 482 ° C. (900 ° Fahr.) to 537 C. (ioooFahr.) 
— and if the work must be maintained bright or scaleless, 
this anneal would be best conducted in a non-oxidizing 
atmosphere, in closed pots, in the presence of carbon 
monoxide gases, charcoal or other substances. For strain 




Fig. 24. 

Globular Cementite. Magnification, 1000 Diameters. 

Carbon content, 1.05 per cent. Annealed at Acl. 

Slowly cooled in furnace. 

anneal we do not care particularly if the micro-structure 
shows lamellar or globular Pearlite. 

For free machining or cold work a structure of con- 
siderable softness and free shearing properties is desired. 
It appears that this can best be attained in high carbon 
steels by heating the steel just below the critical range, 
maintaining this temperature for some time, and then 
cooling very slowly without the presence of drafts, espe- 
cially through latter part of An range. The micro- 
structure will show globular Cementite, as in Fig. 24 — 
that is, the hard constituent (Cementite) will not then 
lie in layers, which are penetrated by the tool with 
difficulty in machining, but will lie like shot in a box in 



32 STEEL AND ITS TREATMENT 

such a way that the Ferrite may be very readily cut and 
the Cementite (in globules) pushed aside. Where steel 
is subject to severe distortion in cold working, this con- 
dition is essential, as it allows Ferrite to flow freely into 
the new form without the splitting, so common when 
laminated Pearlite appears, as in Fig. 25. 

Lower carbon steels may be too soft in the globular 
Cementite condition and to machine properly require be- 




Fig. 25. 

Laminated Pearlite. Carbon content, 1.05 per cent. 
Annealed above Acl. Cooled slowly. 
Magnification, 1000 Diameters. 

ing left in the lamellar form. This is due to the pre- 
dominance of soft Ferrite in these steels with such a 
scarcity of Cementite stiffener that it becomes necessary 
to prevent the flow of the iron under the tool by the lines 
of stiffening Cementite in the form of Pearlite, and to 
obtain this proper cutting- condition in very low carbon 
steels it sometimes becomes necessary to air or even oil 
quench rather than cool slowly. 

When chrome steels are annealed they are frequently 
treated to a preliminary normalizing operation; that is, 



ANNEALING 33 

they are heated above the critical range to remove un- 
equal working strains and to refine the grain. Then they 
are cooled below the critical range and finally annealed 
at the low critical temperature. 

The following ranges of temperatures are recommended 
by the Committee on Heat Treatment of the American 
Society for Testing Materials : — 

Range of Carbon Content Range of Annealing Temperature 
Less than .12 per cent. . . .875° to 925° C. (1607° to 1697° F.) 

.12 to .29 per cent 840° to 870° C. (1544° to 1598° F.) 

" .30 to .49 per cent 815° to 840° C. (1499° to 1544° F.) 

.50 to 1.00 per cent 790° to 815° C. (1454° to 1499° F.) 

They also state that for steels of a manganese con- 
tent greater than .75 per cent, slightly lower temperatures 
are advisable. 

The time at which the steel should be held at an an- 
nealing heat is governed largely by the size of the piece. 
In order to bring the interior of large objects to an ef- 
fective annealing temperature the outside may often be 
heated advantageously somewhat above the desired tem- 
perature. Therefore, a range of temperatures is given 
for each range of carbon content. 

The upper limit of this range applies to larger objects 
and also to the lower range of carbon content given. 

Owing to the annealing process generally being a long 
one and the cooling slow, there is a great opportunity for 
scale (iron oxide) to form on the descending heat, owing 
to the contraction of the furnace gases, in cooling, draw- 
ing in air; hence, if scale is to be prevented this air must 
be kept from the work by closed receptacles. The pre- 
vention of heavy scale, due to cooling from too high 
temperature in the presence of oxygen, is extremely im- 
portant in the case of the higher carbon steels where the 
presence of oxide and heat will serve to oxidize the car- 
bon in the metal nearest the scale (decarbonize) often to 
an injurious degree. 

A thick scale (iron oxide) always represents a depth 
deprived of carbon with a deposit of iron oxide residue. 



34 



STEEL AND ITS TREATMENT 



Carbon oxidizes very rapidly, and when decarbonization 
appears at the surface of hardened steel we find that the 
carbon content of the steel has been lowered for a con- 
siderable distance beyond the depth the fracture would 
indicate. 

The control of the annealing operation by definite heats 
and methods unquestionably prepares steel to respond 




Fig. 26. 
Slip baud caused by burning. 

better to hardening and treating, reduces the strains and 
distortions which are inevitable and paves the way for a 
more uniform finished product. 

In forging or hardening the control of the heats has 
been shown to be highly important. In forging if the 
work is heated too high the operation of forging tends to 
restore correct conditions. The annealing heat, however, 
is usually of such duration that unless cared for the heat 
will rise and the grain size will greatly enlarge. If car- 
ried on further the steel will burn, which will cause fis- 
sures, gas holes in the structure which weaken the steel 
by the loss of cohesion of the crystals and on further 
working or strain slip bands are developed. Fig. 26 



ANNEALING 35 

shows this clearly. The large dark area is a slip band 
caused by burning. 

At times the previous work of forging may have been 
finished at so high a point above the critical range that 
the structure is exceedingly coarse. Annealing at Aci 
will not refine this grain, but if this steel is first heated 
to Ac3 or above, quenched and then annealed at Aci 
and cooled slowly, the resulting structure will thereby 
be refined unless the steel has been burned. 



CHAPTER VI 
PHYSICAL PROPERTIES 

The object of heat treatment is to impart to steel cer- 
tain physical properties to best suit it for a specific use. 
For the present, we will consider only those physical 
properties as are generally specified ; namely, tensile 
strength and hardness values, together with a brief sketch 
of the manner of testing and securing comparative read- 
ings in definite units. We will also show how these tests 
assist in securing the production of large quantities 
of machine parts of uniform physical properties. 

The effect of the additional elements which we know 
steel to contain and their influence on the temperatures 
used in treating will be considered under a different 
heading. 

Tensile Properties 

In referring to the tensile properties of steel, one 
usually implies those properties of the material known as 
the "Elastic Limit," the "Maximum Strength," the 
"Elongation," and the "Reduction of Area." 

A "Stress" is an internal force that resists the change 
in shape and size of any material by an applied force, 
and when the applied forces have reached their final 
values the internal stresses hold them in equilibrium. 
The simplest case is that of a rope, at each end of which 
a man pulls with a force, say 25 pounds ; then in every 
section of the rope there exists a stress of 25 pounds. 
Stresses are measured by the same units as those used 
for the applied forces, and generally in pounds. 

A "Bar" is a prismatic body having the same size 
throughout its length. If a plane is passed normal to the 



PHYSICAL PROPERTIES 37 

bar, its intersection with the prism is called the "cross 
section" or the "section" of the bar, and the area of this 
cross section is called the ''sectional area." 

A "Unit Stress" is the stress on the unit of the sec- 
tion area, and this is usually expressed in pounds per 
square inch. For example : Let a bar, 2 inches square, 
be subjected to a pull of 4,000 pounds ; the resisting stress 
is 4,000 pounds and the unit stress is 4,000 pounds divided 
by the area of the bar, which is 4 square inches, or 1,000 
pounds per square inch. When external forces act upon 
the ends of a bar, in a direction away from its ends, they 
are called "Tensile Forces." When they act towards the 
end they are called "Compressive Forces." A pull is a 
Tensile Force and a push is a Compressive Force, and 
these two cases are frequently called "Tension" and 
"Compression." The resisting stresses receive similar 
designations. A Tensile Stress is that which resists ten- 
sile force. A Compressive Stress is that which resists 
compressive force. 

The terms "Axial Forces" and "Axial Stresses" are 
used to include both tension and compression acting upon 
a bar along the axis of the bar. The first effect of axial 
load is to change the length of the bar upon which it 
acts. The deformation of a bar which occurs in tension 
is called the "Elongation," and that which occurs in com- 
pression is called "Shortening." 

When a bar is subjected to a gradually increasing ten- 
sion the bar elongates, and up to a certain limit it is found 
that the elongation is proportional to the load. Thus 
when a bar of wrought iron one square inch in sectional 
area and 100 inches long is subjected to a load of 5,000 
pounds, it is found to elongate close to .02 inch; when 
10,000 pounds are applied the elongation is .04 inch ; 
when 15,000 pounds are applied the elongation is .06 inch; 
at 20,000 pounds the elongation is .08 inch ; at 25,000 
pounds the elongation is .10 inch. Thus far each addi- 
tion of 5,000 pounds has produced an additional elonga- 
tion of .02 inch, but when the next 5,000 pounds are 



38 



STEEL AND ITS TREATMENT 




o 


o o 


o 


o o 


o 


o o 


0' 


o <* 


*• 


s *» 




UNIT-STRESS IN POUNDS 



o 
o 
o 

6 



OS 



INCH 



PHYSICAL PROPERTIES 39 

added, making a total of 30,000 pounds, it is found that 
the total elongation is about .50 inch, and hence the elon- 
gations are increasing in a faster ratio than the applied 
loads and the resisting stresses. 

Thei "Elastic Limit" is defined as that unit stress at 
which the deformation begins to increase in a faster ratio 
than the applied load. In the above example this limit is 
about 25,000 pounds per square inch, and this is the aver- 
age value of the elastic limit of wrought iron. 

When the unit stress in a bar is not greater than the 
elastic limit, the bar returns on the removal of the load 
to its original length. Thus the above wrought iron bar 
was 100.10 inches long under the load of 25,000 pounds, 
and on the removal of the load it returned to its original 
length of 100 inches. When the unit stress is greater 
than the elastic limit, the bar does not fully return to its 
original length, but there remains a so-called "Permanent 
Set." For instance, let the length of the above bar, under 
a stress of 34,000 pounds, be 102 inches, and on the 
removal of the tension let its length be 101^8 inches. 
Then the permanent set of the bar is 1% inches. 

The "Maximum Strength" is the greatest stress which 
the material will bear before breaking. This corresponds 
to the actual breaking weight in hard steels, but in soft 
steels the actual breaking weight is often considerably 
less. 

The "Elongation" of a bar is determined by mak- 
ing two marks upon it before it is subjected to ten- 
sion, and measuring the distance between them before and 
after the test. The difference between these lengths, di- 
vided by the original length, gives the elongation 
per unit of length. For example : If the distance be- 
tween the two marks is 2 inches and if it becomes 2.60 
inches after the rupture, then the total elongation is .60 
inch in 2 inches and the elongation per unit length is .30 
inch, or 30 per cent. 

An elongation of a bar is always accompanied by a 
reduction in the area of its cross section. The term "Re- 



40 STEEL AND ITS TREATMENT 

duction of Area" refers to a ruptured i specimen, and 
means the diminution in sectional area per unit of original 
area. Thus, if the original area of a specimen is .200 
square inch, and the area of the ruptured section is .080 
square inch, then the reduction of area is .120 square inch, 
which, when divided by the original area, gives .60, or 
60 per cent. The reduction of area is an index of the 
ductility of the material, and is generally regarded as a 
more reliable index than elongation, because the elonga- 
tion is subject to variations with the ratio of the length 
of the specimen to its diameter, whereas the reduction 
of area is more constant. 

A "Tensile Test" of a vertical bar may be made by 
fastening its upper end firmly with clamps and then ap- 
plying successive loads to its lower end. The elongations 
of the bar are found to increase proportionately to the 
loads, and hence also to the internal tensile stresses, until 
the elastic limit of the material is reached. After the 
unit stress has exceeded the elastic limit the elongation 
increases more rapidly than the loads. On soft material 
one will note a marked elongation at the yield point, 
and on a testing machine this is usually accompanied by 
a so-called "Dropping of the Beam." Elongation is ac- 
companied by a reduction of area of the cross section of 
the bar. Finally the maximum strength of the bar is 
passed and it breaks. The load at the yield point, which, 
as mentioned above, is commonly accepted as the com- 
mercial elastic limit, divided by the original section area 
gives the unit stress ; the load which produced the maxi- 
mum strength of the bar when divided by the original 
section area gives the ultimate unit stress. The elonga- 
tion and reduction of area are then measured and cal- 
culated as mentioned above ; thereby one determines the 
tensile test values of the bar. 

Methods of Testing the Hardness of Metaes 

What property in iron and steel is of more importance 
than that of hardness? In some cases, as with a cutting 



PHYSICAL PROPERTIES 41 

tool or a punching die, the metal is practically worthless 
unless it can retain a sharp edge, while in other instances 
where the material has to be machined or cut and trued to 
shape, even a relatively slight increase of hardness is the 
cause of much inconvenience and expense. In a third 
class of material a good wearing surface is of prime im- 
portance, while lastly hardness may often serve as an in- 
dication of a degree of brittleness and untrustworthiness 
which might perhaps be otherwise unsuspected. 

Hardness may be defined as the property of resisting 
penetration or abrasion, and conversely a hard body is 
one which, under suitable conditions, readily penetrates 
a softer material. There are, however, in metals, various 
kinds of manifestations of hardness according to the form 
of stress to which the metal may be subjected. These 
include tensile hardness, cutting hardness, abrasion hard- 
ness and elastic hardness. The usual quantitative tests 
for hardness are static in character, but the conditions 
are profoundly modified when the penetrating body is 
moving with greater or less velocity. The resistance to 
the action of running water, to the effect of a sandblast, 
or to the results of the pounding of a heavy locomotive 
on a steel rail, afford examples of what might perhaps 
for purposes of distinction be called dynamic hardness. 

Five typical methods of measuring hardness include 
the sclerometer, introduced by Turner; the scleroscope, 
invented by Shore ; the form of indentation test adopted 
by Brinell, the drill test introduced by Keep, and the 
Rockwell test. The principles underlying the five meth- 
ods selected for comparison may be briefly described as 
follows : 

Turner's Sclerometer 

In this form of test a weighted diamond point is drawn 
once forward and once backward over the smooth surface 
of the material to be tested. The hardness number is the 
weight in grammes required to produce a standard scratch. 
The scratch selected is one which is just visible to the 



42 STEEL AND ITS TREATMENT 

naked eye as a dark line on a bright reflecting surface, 
or it is the scratch which can just be felt with the 
edge of a quill when the latter is drawn over the smooth 
surface at right angles to a series of such scratches pro- 
duced by regularly increasing weight. 

Shores Scleroscope 

In this instrument a small cylindrical hammer of steel, 
with a diamond point, enclosed in a glass tube graduated 
in arbitrary units, is allowed to fall upon the smooth 
surface of the material to be tested. The hardness num- 
ber is the height of the rebound of the hammer. The 
hammer weighs slightly over two grammes. The height 
of the rebound of hardened steel is in the neighborhood 
of ioo on the scale, or about 160 millimeters, while the 
total fall is about 10 inches, or 225 millimeters. 

Brineu/s Test 

This method is founded upon the effect produced on a 
substance by a known load pressing a ball into the sur- 
face of the material to be tested. The hardness numbers 
are found by the use of certain factors and coefficients, 
and are only arbitrary comparable units, indicating suffi- 
ciently different conditions in the materials tested ; they 
are taken from practical experience rather than from sci- 
entific knowledge. 

The method of working is as follows : The weight 
or load given in kilograms is generally 3000 for iron 
and steel and 500 for softer metals and alloys. The 
pressure is applied hydraulically by means of an oil pump 
and is transmitted through the plunger to a hardened-steel 
ball, which makes a cup-shaped impression on the test 
piece. From the diameter of this impression and the 
load a working - formula has been deduced, and a table 
of hardness numbers computed. 



PHYSICAL PROPERTIES 43 

The formula is as follows : 

H — 3 °°° 



n D , ~ 

(D — y D 2 — d 2 ) 



2 

where 

H = Hardness ; 

D = Diameter of ball (10 millimeters) ; 

d ■=. Diameter of impression. 

The diameter of the impression is read off by means of 
a microscope, having a micrometer scale, graduated in 
tenths of a millimeter, contained in the diaphragm of the 
eye-piece. A verifying scale is supplied with the micro- 
scope. 

Example : Let the diameter of impression = 4.7 mm., 
then 

3000 



H — 



31.416 

- ( IO — V IOO — 22.09) 



disregarding further decimal points 
3000 250 



15.708 X 1. 17 1.309X1.17 



163 hardnesss No. 



This formula is not quite accurate, since it does not take 
into consideration the mass of material displaced but only 
the superficial area of the impression, yet it is perhaps 
the simplest working formula. 

Keep's Test 

In this form of apparatus a standard steel drill is 
caused to make a definite number of revolutions while it 
is pressed with a standard force against the specimen to 
be tested. The hardness is automatically recorded on a 
diagram on which a dead soft material gives a horizontal 



44 STEEL AND ITS TREATMENT 

line, while a material as hard as the drill itself gives a 
vertical line, intermediate hardness being represented by 
the corresponding angle between o and 90 degrees. 

Each form of test has its advantages and its limitations. 
The sclerometer is cheap, portable and easily applied, but 
it is not applicable to materials which do not possess a 
fairly smooth reflecting surface, and the standard scratch 
is only definitely recognized after some experience. The 
Shore test is simple, rapid and definite for materials for 
which it is suited. As shown by De Freminville, the 
result obtained varies somewhat with the size and thick- 
ness of the samples, while if the test piece is supported 
on a soft material, such as plasticine, the results are 
valueless. 

The Brinell test is especially useful for constructive 
material. It is easily applied and definite and is the hard- 
ness test most generally employed ; it cannot be applied 
to very brittle materials, such as glass or hard minerals. 

A very important question arises in connection with 
these various tests ; namely, as to whether there is any 
observed agreement between the results which are ar- 
rived at by such entirely different methods. It will be 
noticed that in each case an arbitrary scale is adopted. 
If the weight used on the sclerometer had been ounces 
instead of grammes the hardness numbers would naturally 
have been different. Similarly BrinelFs test might have 
been expressed in tons and inches, or a definite weight of 
hammer and height of scale adopted by Shore. Hence, 
all that can be expected is a proportionality in the results, 
and if this is ascertained it should be possible to convert 
values on one scale into results on another. In the fol- 
lowing table will be found a comparison of hardness 
values of various materials. For the purpose of compari- 
son, the actual Brinell hardness values have been divided 
by 6. The sclerometer and scleroscope values are actual 
readings. It appears, from a study of the table, that all 
the instruments with simple homogenous substances give 
results which are either in actual agreement with or pro- 



PHYSICAL PROPERTIES 



45 



portional to the results obtained by the other form of 
apparatus. 

Rockwell Testing Machine For Hardness 

This machine consists of an anvil and a plunger holding 
a diamond point. The diamond is forced into the sur- 
face of the steel under a constant pressure. The depth 
of the impression is read direct to 1/10,000 of an inch. 
The machine is calibrated to give a hardness reading in 
Brinell numbers or in percentages. Electrolytic iron is 
taken as Zero per cent, and the diamond as ioo per cent. 
Hard. It can be used excellently as a comparative tester. 
Due to its small area of application a great many shapes 
and surfaces may be tested accurately. Wire can be 
tested as small as .09 inch diameter. It requires no 
special preparation of the piece of steel to be tested except 
in some cases a slight surface cleaning. The depth of 
indentation can be controlled so that no harm can be 
done to a finished surface. 



TABLE No. I. 

HARDNESS VALUES OF METALS. 



Metals 


Sclerom- 
eter 


Sclero- 
scope 


Brinell 


Lead 

Tin 

Zinc 

Copper (soft) 


1.0 
2.5 
6.0 
8.0 

15.6 

21.0 

21-24 

24.0 

36.0 

72.0 

.... 


1.0 
3.0 
7.0 
8.0 
12.0 

22.6 

24.0 
27.0 
40.0 
70.0 
95.0 


1.0 

2.5 

7.5 


Copper (hard) 

Softest Iron 


12.0 
14.5 


Mild Steel 


16.24 


Soft Cast Iron 


24.0 


Rail Steel 


26-35 


Hard Cast Iron 


35.0 


Hard White Iron 


75.0 


Hardened Steel 


93.0 







46 



STEEL AND ITS TREATMENT 



TABLE No. II. 

BRINNBLL HARDNESS NUMBERS AND ESTIMATED TENSILE 
STRENGTH FOR 3,000 KILOGRAM PRESSURE ON A 
10 M/M BALL TESTING MACHINE. 



Dia. of 




Ultimate 


Dia. of 




Ultimate 


Impression 


Hardness 


Pounds 


Impression 


Hardness 


Pounds 


in m/m 


Numeral 


per Sq. In. 


in m/m 


Numeral 


per Sq. In. 


2.00 


946 


465,100 


4.00 


228 


112,600 


2.05 


898 


442,100 


4.05 


223 


109,700 


2.10 


857 


421,600 


4.10 


217 


106,900 


2.15 


817 


402,000 


4.15 


212 


104,200 


2.20 


782 


383,700 


4.20 


207 


101,600 


2.25 


744 


366,600 


4.25 


202 


99,100 


2.30 


713 


350,600 


4.30 


196 


96,700 


2.35 


683 


335,700 


4.35 


192 


94,400 


2.40 


652 


321,600 


4.40 


187 


92,200 


2.45 


627 


308,400 


4.45 


183 


90,000 


2.50 


600 


295,900 


4.50 


179 


87,900 


2.55 


578 


284,300 


4.55 


174 


85,800 


2.60 


555 


273,300 


4.60 


170 


83,900 


2.65 


532 


262,900 


4.65 


166 


82,000 


2.70 


512 


253,100 


4.70 


163 


80,100 


2.75 


495 


243,800 


4.75 


159 


78,300 


2.80 


477 


235,000 


4.80 


156 


76,600 


2.85 


460 


226,600 


4.85 


153 


74,900 


2.90 


444 


218,700 


4.90 


149 


73,300 


2.95 


430 


211,200 


4.95 


146 


71,700 


3.00 


418 


204,100 


5.00 


143 


70,200 


3.05 


402 


197,300 


5.05 


140 


68,700 


3.10 


387 


190,800 


5.10 


137 


67,200 


3.15 


375 


184,600 


5.15 


134 


65,800 


3.20 


364 


178,800 


5.20 


131 


64,500 


3.25 


351 


173,200 


5.25 


128 


63,100 


3.30 


340 


167,800 


5.30 


126 


61,800 


3.35 


332 


162,700 


5.35 


124 


60,600 


3.40 


321 


157,800 


5.40 


121 


59,400 


3.45 


311 


153,100 


5.45 


118 


58,200 


3.50 


302 


148,600 


5.50 


116 


57,000 


3.55 


293 


144,300 


5.55 


114 


55,900 


3.60 


286 


140,200 


5.60 


112 


52,800 


3.65 


277 


136,200 


5.65 


109 


53,700 


3.70 


269 


132,400 


5.70 


107 


52,700 


3.75 


262 


128,800 


5.75 


105 


51,700 


3.80 


255 


125,300 


5.80 


103 


50,700 


3.85 


248 


121,900 


5.85 


101 


49,700 


3.90 


241 


118,700 


5.90 


99 


48,800 


3.95 


235 


115,500 


5.95 


97 


47,900 



Pressure 



Area of Impression 



= Hardness Number 



Tensile in Kg. per sq. m/m = coefficient .346 X hardness number 
1422.3 Factor to convert Klg. per sq. m/m to lbs. per sq. in. 



CHAPTER VII 

PYROMETERS 

In the heat treatment of steel too great emphasis cannot 
be laid upon the controlling and regulating of the tem- 
perature of heating, whether it be for hardening, drawing 
or annealing. In the treatment of steels where the crit- 
ical changes must be determined and the furnace regu- 
lated to the predetermined heat we are forced to depend 
on the pyrometer. 

In the heat treatment of steel the types of pyrometers 
most generally used are the thermo-electric pyrometers 
and optical pyrometers. Of these two the thermo-electric 
method is by far the most important. 

The theory on which the operation of thermo-electric 
pyrometers is based is briefly described as follows : 

If, when two wires of different composition are joined 
together at both ends so as to make a complete circuit, 
one of these junctions be at a different temperature from 
the other, a difference of electrical potential is set up at 
the junctions and an electric current flows through the 
wires. Such a pair of wires is called a thermo-electric 
couple. If the wires are of uniform composition the po- 
tential difference depends upon the difference of tempera- 
ture alone, and the strength of the current will vary 
directly as the differences of temperature. If a galva- 
nometer or a millivoltmeter be inserted in the circuit, this 
current can be measured, and if the current correspond- 
ing to various differences of temperature be once ascer- 
tained, the apparatus can be used as a means of meas- 
uring temperature. The thermo-electric couples are di- 
vided into two principal classes : Base Metal and Noble 
Metal couples. 



48 STEEL AND ITS TREATMENT 

There appears to be an insistent demand on the part 
of many in charge of technical processes requiring tem- 
perature control for inexpensive and robust measuring 
apparatus. For this reason, if for no other, the use of 
the base metal couple has become firmly established and 
its success lies principally in the production of fairly satis- 
factory alloys having considerable changes of electro- 
motive-force with small temperature changes, which can 
be made into strong, practically unbreakable, thermo- 
couples, and the development of an inexpensive fairly 
robust millivoltmeter. 

Practically all the base metal thermal couples in com- 
mercial use at present are made of one of the follow- 
ing combinations : iron-copper-nickel ; nickel-chrome- 
nickel-aluminum ; or nickel-copper-nickel-chrome. 

The former are more efficient when used in furnaces 
in a reducing atmosphere. The latter are more desirable 
in an oxidizing atmosphere. 

The standard noble metal couple is made of platinum 
and an alloy of platinum with 10% of Rhodium. 

The thermo-electric force of these various base metal 
couples is quite constant and is in the majority of cases 
unaffected by furnace gases. Sometimes, however, the 
materials of the couple may be altered in a uniform man- 
ner by the heat and minor errors introduced. Further, 
the heat of the furnace is almost sure to cause the ma- 
terials to disintegrate, thus reducing the cross section of 
the couple and increasing its resistance. This increase 
in resistance allows less current to flow for a given electro- 
motive force and is the source of serious errors. 

It is, therefore, important to frequently check and cali- 
brate a pyrometer consisting of a base metal couple and 
a millivoltmeter. 

The noble metal couple has its advantages. It pos- 
sesses a fairly linear temperature electro-motive-force 
relation, especially so between 300 and 1100 C. (572 
and 2012 Fahr.). It can be used at temperatures as high 
as 1500 C. (2732 Fahr.) with great accuracy. Properly 



PYROMETERS 49 

protected it can be retained in a homogeneous condition, 
so that depth of immersion in the furnace or heating 
medium brings about little or no error, and on account of 
its being used in connection with a high resistance gal- 
vanometer, errors due to changes in lead resistance and 
that of the couple itself are usually negligible. 

Heating noble metal pyrometer couples to high tem- 
perature in a reducing atmosphere causes an alteration 
of the elements. 

Platinum couples must be protected by some form of 
ceramic case which is impermeable to hot gases, other- 
wise the couple will be seriously damaged by hydro- 
carbon gases and metallic vapors from the furnace. The 
two wires should be insulated from each other by quartz 
or clay tubing. Avoid the use of asbestos, as the material 
in its pure form probably has no action, but practically 
all commercial asbestos available contains impurities 
which have an injurious effect on platinum. 

A couple thus mounted is limited only by the melting 
point of the protective tube and insulators. These are 
available up to 1371 C. (2500 Fahr.) but must be used 
with great care. 

An iron tube can be used for protection if the tem- 
perature does not exceed 8oo° C. (1472 Fahr.), in the 
lead bath serving to harden steel for example, and for 
movable couples which are exposed to heat only during 
the time necessary to take the observation. In all cases 
where the furnace, whose temperature it is desired to 
measure, is under reduced pressure, suitable precautions 
must be taken to prevent any permanent entrance of cold 
air by the orifice necessary for the introduction of the 
tube, before as well as during an observation. Otherwise, 
one runs a chance of having inexact results. 

In the case of prolonged observations in a reducing at- 
mosphere or in contact with melted bodies, the couples 
should be protected by enclosing in a covering im- 
permeable to the melted metals and to vapors. 
5 



50 STEEL AND ITS TREATMENT 

Whether the couples be made of base or noble metal, 
for good, accurate service the wire should be well insu- 
lated and the junction of the elements protected from the 
gases of the furnace, the cold-end junction kept fairly 
constant, the accuracy of the system checked or calibrated 
frequently, depending on the temperature and length of 
time in service (for checking, a standard millivoltmeter 
and couple is often set aside and used only for the above 
purpose) and the entire system handled with care, for in 
the majority of cases errors and false readings, as well 
as lack of confidence in the pyrometer, is caused by the 
abuse or wrong use of the apparatus. 



CHAPTER VIII 
THE THERMAL OR HEAT TREATMENT OF STEEL 

The highest priced steel may be so improperly treated 
that the results or properties obtained are far inferior 
to a well-treated, cheaper grade of steel. Although these 
changes, due to the thermal treatment, are governed by 
definite laws it must be remembered that the same treat- 
ment cannot be applied to all steels with satisfactory re- 
sults, but that each type of steel responds best to its own 
characteristic temperatures. 

The subject of heat treatment embraces the operations 
of annealing, case-hardening or carburizing, hardening, 
and tempering or drawing of steels. To obtain the high- 
est physical properties from steel by heat treatment it is 
necessary for us to have a knowledge of the critical 
points and transformations occurring. 

An improvement in the quality of physical properties 
of the steel is generally brought about by heating to or 
through the critical range. Hardening or annealing from 
temperatures below these points will not be complete, nor 
will the structure or grain be properly refined. Quench- 
ing from temperatures higher than the critical range will 
result in hardening the steel, but with a coarser grain 
than if quenching had been done at just above the critical 
range. 

It is universally understood that the finer the grain 
the stronger the steel, and to obtain this refinement the 
heating and cooling curves of the steel must be deter- 
mined and the treatment operation confined as narrowly 
as possible, with respect to the critical temperatures, else 
the worth of the steel will be markedly impaired. 



52 STEEL AND ITS TREATMENT 

These facts about the internal modification of the steel 
structure present some very interesting viewpoints to the 
practical man familiar with them. For instance, if a cold 
piece of steel (the higher the carbon the more aggravated 
it becomes) is thrown into a raging hot furnace (much 
above the critical range) the transformation of the Pearl- 
ite and the Ferrite, or Cementite into Austenite, is rushed 
far beyond the capacity of the steel to withstand it, and 
in passing into the Austenite stage a molecular expan- 
sion occurs. Thus the phenomenon of cracking 
on a rising heat is explained. Similarly, if flame impinges 
upon the work, the transformation takes place very fast 
at this point and either cracking or warping must en- 
sue. This is why muffle furnaces and lead or salt baths 
give much better hardening results as a rule. Besides 
this, in a salt bath, upon the introduction of a piece, the 
salt congeals about the work, melts fairly slowly and 
serves to help in the slowing down of the transformation. 
Preheating to a medium temperature before insertion in 
the hardening furnace also helps the steel pass through 
this critical stage without damage. 

Changes of Structure: Brought About By Heat 

Treatment 

These changes have been summarized by Brinell about 
as follows : 

i. When a piece of steel, hardened or unhardened, is 
heated to the upper critical point, Ac3, all previous 
crystallization, however coarse or however distorted by 
cold work, is obliterated and replaced by the finest struc- 
ure which the steel is capable of assuming, the structure 
of burnt steel being the only exception (the Ferrite and 
Pearlite or Pearlite and Cementite is changed to Au- 
stenite) . 

2. When a piece of steel, hardened or unhardened, 
after being heated to Ac3, is allowed to cool slowly, it 
retains the fine structure which it had acquired at that 



THE THERMAL OR HEAT TREATMENT OF STEEL 53 

temperature. It then possesses the finest structure which 
unhardened steel is capable of assuming. (The Austen- 
ite reverts to the original Pearlite and Ferrite or Pearlite 
and Cementite, but the grains, however coarse originally, 
become now the finest and best distributed possible.) 

3. When a piece of steel, hardened or unhardened, 
after being heated to Ac3, is suddenly cooled by quench- 
ing in cold water, for instance, it is fully hardened 
and retains the fine grain acquired at that temperature. 
The metal then possesses the finest structure which hard- 
ened steel is capable of assuming. 

(The Austenite, which tends to rapidly revert through 
several stages to Pearlite, etc., is trapped before reaching 
the soft Pearlite stage and the resulting structure is com- 
posed of Martensite — the hardest stage in steel, save the 
Cementite, and the condition of greatest volume.) 

4. When a piece of steel, hardened or unhardened, is 
heated to a temperature above Ac3 and cooled slowly, 
the metal whose crystallization has been obliterated by its 
passage through Ac3, crystallizes again, the crystals or 
grains increasing in size until An is reached, below which 
there is no further growth. 

If steel is heated above Ac3 and allowed to cool to 
Ac3 again and there quenched, it will be fully hardened, 
but its structure will be coarser than if it had been 
quenched from AC3 without having been heated higher. 

5. The higher the temperature above Ac3, from which 
the steel is cooled or quenched, the coarser the grain. 

6. The slower the cooling from above Ac3 the coarser 
the grain. 

7. When a piece of hardened steel is heated to a tem- 
perature below AC3 some of its Cementite is changed 
spontaneously into Pearlite and the metal is thereby soft- 
ened. This tendency increases with the temperature and 
is greatest at Aci. This transformation, however, is not 
accompanied by a change in the dimension of the grain. 

Our researches and the recent work of Professors 
Howe and Zimmerschied have developed that : 



54 STEEL AND ITS TREATMENT 

i. When a piece of steel, hardened or unhardened, is 
heated to the temperature Aci, the Cementite existing in 
the Pearlite structure is radically altered from the prev- 
ious laminated to the globular state, the resultant struc- 
ture is thereby softened and rendered ductile, and the 
size of the grain is unchanged. 

2. When a piece of steel, previously heated to Ac3 
and then either hardened or allowed to cool slowly, is 
thereupon heated to Aci and allowed to cool slowly, espe- 
cially through the lower An range, the resultant structure 
shows globular Cementite and is the softest and most 
ductile that steel may assume, the size of the grain being 
the smallest possible. 



. CHAPTER IX 

CARBURIZING 

Carburizing has risen in the past ten years from a 
practice of which very little was written and very little 
known to a position that has assumed great commercial 
importance, due primarily to the rapid development of 
the motor car industry. 

It is the demand of this industry to meet the develop- 
ment where greatest strength and minimum weight are 
essential that has given the impetus to the marked ad- 
vance in metallurgy, making necessary a corresponding 
improvement in heat treating practices in both alloy and 
straight carbon steels. While present-day methods pro- 
duce results revolutionary in comparison with those of 
only a few years past, the science is far from being a 
completed one today. 

With the knowledge that present-day methods may 
in turn be discarded a few years hence this work is sub- 
mitted. It contains the most up-to-date practices today 
and is intended to act merely as a guide from which 
the individual hardener may select the information that 
will be most helpful in his particular case. 

The theory of carburizing depends upon the fact that 
steel and iron has such strong affinity for carbon that 
when heated in a sealed receptacle in contact with car- 
bonaceous material the carbon gas is absorbed by the 
metal. 

The operation of carburization implies that the user 
in a sense makes his own steel, and the details of the 
operation must be thoroughly understood so that it may 
be conducted with a minimum cost and with the maximum 
certainty and regularity. 



56 STEEL AND ITS TREATMENT 

Investigation has proved that the advantages accruing 
from case carburizing make it the most efficient manner 
of obtaining the desired physical properties in many cases. 

Opinions vary as to the theory of the absorption of 
carbon by the metal. The carbon may combine with the 
iron at the surface to form carbides which diffuse in the 
metal, or the carbon may be diffused in a gaseous condi- 
tion, the gas giving up its carbon to the metal. 

Whatever may be the method, the facts indicate that 
the best results are obtained when carbonaceous vapors or 
gases are present. 

The process of carburizing is one which consists of 
adding such a percentage of carbon to an outside layer 
of steel as will, on correct quenching, produce a hard- 
ened surface, while the inner core of the metal retains its 
initial character. 

In carburizing we desire to control two factors: First, 
the depth of the carburized zone ; second, the graduation 
of the carbon content from the outer surface to the core. 

The percentage of carbon and the depth of penetration 
are dependent upon, first, the composition of the steel 
subjected to carburization ; second, the carburizing tem- 
perature ; third, the length of time the steel is allowed 
to remain at the carburizing heat; fourth, the nature of 
the carburizing material used. 

Composition of St££i,s For Carburizing 

It is a well-known fact that low carbon steels are more 
susceptible to carburization than those of high carbon 
content, which explains the decreased rate of penetration 
during the latter part of the carburizing operation. 

Then, again, on using low carbon steels for carburiza- 
tion the resultant core remains tough, soft and fibrous 
and enables the finished product to resist shock. 

The initial carbon content of the steel governs the depth 
of case at which maximum brittleness and minimum 
strength occur, so that the higher the original carbon con- 



CARBUR1ZING 57 

tent the lower the ratio of depth of case to the diameter 
of the core. Therefore, it is important to know that depth 
of carburizing is partly regulated by the carbon content 
of the original steel. 

Some constituents retard the rate of penetration, others 
increase it, while some increase brittleness and others re- 
duce it. 

The carbon content of the steel should be below 25 
point, as the higher the carbon content the greater the 
brittleness after heat treatment. 

Manganese content should be about .35 per cent, or less, 
as high manganese renders the carburized case brittle 
and lowers the resistance to shock. Manganese increases 
the rate of penetration. 

If, however, steel with higher manganese content is 
used, the detrimental effects can be overcome by alloys, 
such as nickel and chromium. 

Silicon retards the rate of penetration; in fact, steels 
containing over 2 per cent, of silicon will not absorb 
carbon. In general, it should not exceed .30 per cent. 

Phosphorus and sulphur content should be low. 

Nickel very materially affects the physical properties, 
the effect being limited by the amount of nickel and the 
carbon present. 

Nickel lowers the rate of penetration in proportion to 
the amount present, when in excess of 2\ to 3 per cent. 

Vanadium lowers the rate of penetration, but as it is 
used in such small quantities, its effects in this respect 
may be disregarded. Its influence on the physical prop- 
erties is pronounced, and it very materially increases 
strength, elastic limit and resistance to shock. 

Chromium increases the rate of penetration of carbon 
and reduces the grain size considerably. 

It slightly increases the difficulties of machining and 
forging. 

The composition of any steel for carburizing should be 
regulated for the purpose intended. 



58 STEEL AND ITS TREATMENT 

A fair analysis of a carbon steel for general work is 
carbon 10 to 20 point, manganese and silicon less than 
.35 per cent., phosphorus and sulphur below .04 per cent. 

The influence of the different elements on the speed of 
penetration of carbon, when carburizing steels containing 
the same amount of carbon and the different percentages 
of manganese, chromium, nickel and silicon, is shown in 
the following comparative table : 

INFLUENCE OF ALLOYS ON CARBON PENETRATION. 

Speed of 
Penetration 
per Hour 
Component of Alloys in Indies 

0.5% Manganese 043 

1.0% " 047 

1.0% Chromium 039 

2.0% " , 043 

2.0% Nickel 028 

5.0% " 020 

0.5% Silicon 024 

1.0% " 020 

2.0% " 016 

5.0% " 000 



Carburizing Temperature 

The carburizing temperature and its uniformity con- 
trols the degree of carburizing. 

While the theory has been advanced that carburiza- 
tion may take place at temperatures below the critical 
range, experience has proved that the low temperatures 
are very unsatisfactory for commercial work. The slight 
carburized zone obtained at a temperature of 705 ° C. to 
788 C. (1300 Fahr. to 1450 Fahr.) with the ordinary 
grades of carburizing steels is lacking in uniformity, low 
in carbon content and with little graduation. 

There are a few special steels, however, principally the 
chrome vanadium steel, which absorb carbon quite readily 
at low temperatures. 



CARBURIZING 



50 



The carburizing temperature is dependent upon the 
carburizing material used, inasmuch as some materials 
will give a 90-point case at 87 1° C. (1600 Fahr.), 105- 
point case at 899 ° C. (1650 Fahr.), 115-point case at 



Fig. 28. 

Depth of Penetration. 

Carburized twenty-four hours at 874° C. (1605° Fahr.). 




Fig. 29. 

Depth of Penetration. 

Carburized twenty-four hours at 925° C. (1697° Fahr.). 

927 ° C. (1700 Fahr.), while other materials may give 
a 90-point carbon case at 927 ° C. (1700 Fahr.). 

It is absolutely necessary to be thoroughly familiar with 
the carburizing material, the results obtained at cer- 
tain heats, length of time required to obtain a certain 



CO STEEL AND ITS TREATMENT 

depth of penetration at that temperature, and whether 
the heats used will injuriously affect the steel. 

A temperature of 899 C. (1650° Fahr.) is best for 
most purposes, taking into consideration the demand for 



-p-T" 





Fig. 30. 

Depth of Penetration. 
Carburized twenty-four hours at 1010° C. (1850° Fahr.). 

quick carburizing, with retention of the physical proper- 
ties of the steel. 

The carburizing temperature influences the depth of 
penetration. The higher the temperature used in car- 
burizing the greater the depth of penetration, as shown in 
Figs. 28, 29 and 30. Fig. 28 represents a piece of steel 
carburized for 24 hours at a temperature of 874 C. 
( 1605 Fahr.), and shows the least penetration, where- 
as the piece carburized for 24 hours at a temperature of 
925 ° C. (1697 Fahr.), shows a decided deeper penetra- 
tion of case (Fig. 29) and Fig. 30, which was carburized 
for 24 hours at a temperature of 1010 C. (1850 Fahr.), 
gives the deepest case of all. 

In hastening the carburizing operation the furnaces 
may be heated to 50 Fahr. above the carburizing tem- 
perature until the pots are heated throughout and then 
lowered to the correct carburizing temperature. 



CARBURIZING 61 

After the carburizing pots have been heated throughout 
the heat must be kept as uniform as possible, so as to 
obtain the best results. 

In commercial work, however, there are so many things 
to be taken into consideration that we think it best to 
summarize the effects of the temperature and thus allow 
our readers to make their selection. 

As a further aid to the hardener, the specifications of 
the American Society of Automotive Engineers are given 
at the close of this treatise. It will be seen that the 
general characteristics are given, together with the heats 
for carburizing and heat treatment. These heats are ap- 
proximate, but in very close range for proper refining. 

The: Depth of Penetration 

The depth of penetration in a given time, as well as the 
carbon content or percentage of carbon in the carburized 
zone, is governed by the temperature used in carburiz- 
ing and the length of time the work is held at the car- 
burizing heat. 

The higher the temperature used in carburizing the 
greater the depth of penetration and the higher the car- 
bon content of the carburized case, all of which has 
been proved by tests made by heating the same work 
under the same conditions but increasing the carburizing 
temperature for each new heat or test. 

The lowest temperature at which uniform penetration 
can be obtained is about 8i6° C. (1500 Fahr.). 

Work which is not "subjected to shock," but requiring 
the greatest wearing surface, can be carburized at a tem- 
perature of 927 C. (1700 Fahr.), with a suitable car- 
burizing material to obtain a carburized case of Hyper- 
Eutectoid composition or 115-point carbon, as shown 
in Fig. 31. 

This micro-photograph shows the black areas as Pearl- 
ite and the white areas surrounding the Pearlite as ex- 
cess carbide or "Free Cementite." 



62 



STEEL AND ITS TREATMENT 



Such parts as ball and roller bearings, which require 
the toughest possible case with the greatest hardness, 




Fig. 31. 

Dark Areas, Pearlite. 

White lines, Excess Carbide or "Free Cementite." 

should be carburized at 900 C. (1652 Fahr.), so as to 
obtain a carburized case of Eutectoid composition or 90- 
point carbon, as shown in Fig. 32, since the presence of 
"Free-Cementite" in the carburized case would produce 
brittleness when subjected to shock and heavy load. 

For a given time and temperature the chrome steels 
seem to give the greatest depth of penetration, as well as 
the highest carbon content. 

Graduation of case into core increases with the in- 
crease of temperature in carburizing, attaining a maxi- 
mum at about 912 C. (1675 Fahr.). Grain size of the 
steel increases with increased temperature. 



CARBURIZING 63 

Alloy steels, especially chrome vanadium, show the 
least coarse crystallization at high temperature. 

Conditions in working, cost of hardening, haste for 
parts needed in production, etc., necessitate that the prac- 
tical man make a close study of his work. Results, while 
not carrying the steel to the highest degrees of hard- 
ness, but sufficient for present needs, can be obtained by 
a close study of the effect of high carbon case, light or 
thin penetration, quenching directly from the carburiz- 
ing pot, or allowing the work to cool in the pots and 
reheating to the hardening temperature. 

The above methods are used by many hardeners, know- 
ing that they are not obtaining the greatest efficiency in 
the piece treated, but time, conditions in the shop and 
the cost of production are the excuses for hastening or 
changing the method to obtain the best possible results, 
such as cooling in the carburizing pot and heating for 
core refinement, heating for case refinement and drawing, 
if necessary. 

A carburized case of great depth and high carbon con- 
tent may cause warpage, cracking and brittleness on small 
parts, while a thin, low carbon case is of no value to the 
work other than the benefit the piece receives from the 
heating and quenching. 

The selection of the best carburizing temperature to 
obtain uniform work of the highest standard requires con- 
sideration of the composition of the steel to carburize, 
shape of the boxes, fuel, cost of production, etc., all of 
which we can touch lightly, leaving much to the judg- 
ment of the individual to regulate conditions under his 
control. 

The microscope plays an important role in determining 
the depth of the carburized case and also the carbon con- 
tent of the case. It is possible by microscopic examina- 
tion of steel, which has been annealed and cooled slowly, 
to determine the percentage of carbon. The carburized 
case can be divided into three classes : 



64 



STEEL AND ITS TREATMENT 



4% 



y^t' 






V\\ 



■-*&■ 







CARBURIZING 65 

First, the Hypoeutectic layer in which the amount of 
carbon is less than .85 per cent., as shown in Fig. 32. 

Second, the Eutectic layer containing .85 to .90 per 
cent, carbon, as shown in Fig. 32. 

Third, the Hypereutectic layer in which the amount of 
carbon exceeds .85 per cent., shown in Fig. 32. 

To prepare a piece of carburized steel for examina- 
tion cut in two and polish the cross section with two or 
three grades of emery wheels or emery paper, finishing 
with the finest grade, and finally with rouge, until a mir- 
rorlike finish is obtained. The polished section is then 
immersed in a solution of 10 parts picric acid and 90 
parts alcohol, or 5 parts nitric acid, 95 parts alcohol for 
30 seconds. The carburized layer will be darkened by 
the action of. the acid, and the three zones, hypoeutectic, 
eutectic and hypereutectic, will show up distinctly. 



CHAPTER X 
CASE-HARDENING 

The factors which control case-hardening are: First, 
carburizing materials used; second, style of boxes and 
method of packing; third, the temperature reached; 
fourth, the length of time held at this temperature ; fifth, 
the heat treatment after carburizing; sixth, the method 
of hardening, quenching and tempering; seventh, the 
character of the metal treated. 

A molten bath of potassium cyanide heated to 850 C. 
(1562 Fahr.), and in which the steel articles are im- 
mersed, produces quick, superficial, hard and even cases. 
The poisonous character of the escaping gases, however, 
is a serious objection to its use. 

The carburizing of steel may also be performed at the 
proper temperature by means of gases, such as illuminat- 
ing or other gases rich in hydro-carbons. There are a 
number of commercial mixtures offered for sale, all of 
which possess some or a number of good virtues. 

A perfect carburizing material should possess the fol- 
lowing virtues : 

First — Should carburize quickly, so that the heating 
will be extended over the shortest possible time. 

Second — It must be homogeneous. 

Third — It must carburize at a uniform rate. 

Fourth — It must give a uniform carbon content. 

Fifth — It must not exhaust itself too quickly; that is, 
it must be capable of being used over and over again 
without complete renewal of fresh material. 

Sixth — Must be free from sulphur and moisture. 



CHAPTER XI 
CARBURIZING MATERIAL 

A fairly rapid heating carburizing material may, in 
some instances, be desirable ; it is by no means essential. 
The rate of penetration of carbon in any grade of steel 
is normally governed by the temperature used in car- 
burizing and the carburizing gases liberated by the ma- 
terial at the carburizing temperature. 

The effect of increasing the temperature is to increase 
the solubility of the carbon in the steel. 

All carburizing mediums do not give the same rate of 
penetration at the same temperature. 

Charcoal and coke are not so rapid as leather, bone and 
other compounds rich in hydro-carbons. 

The freedom with which the carburizing gases are lib- 
erated depends entirely upon the composition of the mix- 
ture and the form in which the carbonaceous material 
exists. It is generally conceded that carbon monoxide is 
the true carburizing gas, and is developed from solid car- 
burizers by the influence of heat — indirectly from the de- 
composition of hydro-carbon vapor and cyanogen and di- 
rectly from the oxidation of the fixed carbon. The hydro- 
carbons and cyanogens are much more easily volatilized 
by heat than the fixed carbons, which are more graphitic 
in their nature, especially those of mineral origin. 

A compound may thus have a high heat conductivity 
and yet, being composed largely of fixed carbon, will not 
liberate and form the carburizing gases in any quantities 
until the higher temperatures are reached. It is not cor- 
rect, therefore, to assume that all carburizers are equally 
efficient in their rate of penetration at any one tempera- 



68 STEEL AND ITS TREATMENT 

ture, whether that heat is 8i6° C. (1500 Fahr.) or 927 
C. (1700 Fahr.). 

One point necessary in case-hardening is absolute con- 
trol over the carburizing temperatures, especially if the 
work is to be subsequently heat treated. Under such con- 
ditions the carburizing heats must be carried as close to 
the critical range of the steel as possible, and yet give a 
satisfactory case. If this were not essential carburizing 
temperatures could be carried to 1038 C. (1900 Fahr.), 
and even above and the time materially shortened. 

The short heats are not the object, as longer and lower 
ones are given to prevent overheating the steel. The 
effect of high temperature on steel is a coarse granular 
structure which is refined only with the greatest difficulty. 
This is especially true on case-hardened work, as it is 
difficult to refine the core, and the high heat required for 
this renders the high carbon case exceedingly weak and 
brittle, with a tendency to chip. 

Case-hardening does not improve the quality of the 
steel under the most favorable conditions, and the hard- 
ener knows it is better to never overheat the metal than 
try to restore an overheated condition. 

To prevent this overheating, therefore, expensive in- 
stallations of pyrometers are used in connection with the 
furnaces, and much care is taken that no variations in 
the carburizing temperatures occur. 

There are carburizing materials on the market whose 
heats cannot be controlled by pyrometers, due to internal 
combustion occurring in the pots which raise the heat of 
the mixture above that indicated by the millivoltmeter. 

The following experiment was conducted to determine 
internal heat of carburizing materials, together with their 
thermal conductivity : 

A round box, 8 inches in diameter, filled with the mix- 
ture was submerged in a molten salt bath to one inch of 
the top of the pot. Two thermocouples were used cali- 
brated with each other. One of these was placed in the 
molten bath and the other in the pot through a hole in 



CARBURIZING MATERIAL 69 

the center of the lid, which was afterwards carefully 
luted with clay. 

After giving the bath sufficient time to thoroughly heat 
the contents, readings were taken. The temperature of 




Fig. 33. 
Coarse crystallization of case, or "freckled corners." 

the molten salts registered 927 ° C. (1700 Fahr.), and 
the temperature of the carbonizing material was 1008 
C. (1846 Fahr.), or 146 Fahr. higher than the applied 
heat. 

The results of this test indicate plainly that a com- 
bustion was occurring in the pot which raised the tem- 
perature higher than that indicated on the instruments. 

Fig. 33 represents a piece of steel carburized with 
a carburizing material of such nature. The coarse 
crystallization of the outer surface of the case which was 
not refined by a double heat treating is plainly shown. 
This coarse crystallization of the case is a detriment, 
as it causes brittleness and chipping of the case. 

The rapidity with which a mixture will transmit heat 
depends largely on its density. Material that is finely 
powdered will not heat as rapidly as material which is 
coarse. Material that is porous will convey heat more 
rapidly than material that is solid, due to free circulation 
of heated gases inside the pot. 



70 



STEEL AND ITS TREATMENT 







Fig. 34. 
Surface decarburization. 




Fig. 35. 
Surface decarburization. 



CARBURIZING MATERIAL 



71 




Fig. 36. 
Uneven penetration. 







Fig. 37. 
Uneven penetration. 



72 STEEL AND ITS TREATMENT 

However, it does not follow that coarse and porous 
material is more efficient in its penetrating power on the 
steel than the solid and powdered material. 

The value of a carburizing agent also depends on the 
kind of gases developed by the heat applied. 

Some materials give off oxidizing gases, which oxidize 
the carburized work and result in that condition known 
as surface decarburization. 

We have known of several instances where all the steel 
carburized in one heat would not harden by quenching, 
even after the carburizing operation was repeated, yet 
the broken part showed a good depth of case. Cuts were 
taken from the outer layer, and upon analysis showed a 
surface decarburization to a depth of .008 of an inch and 
a carbon content of .56 per cent. The second cut of .01 
inch gave a carbon content of .86 per cent. Figs. 34 and 
35 indicate a decarburized condition very plainly. 

Usually decarburization occurs only with a weak car- 
burizer and with low carburizing temperatures. 

Surface decarburization never occurs when a reducing 
atmosphere is maintained by the presence of hydro-car- 
bon gases. This point is mentioned because the mate- 
rials, such as bone, etc., showing slow heat conduction, 
are rich in hydro-carbons, while in the materials with 
the greatest thermal conductivity the hydro-carbons are 
entirely lacking. 

All carburizing agents have one detrimental feature 
or more. One compound may be dusty, and the fumes 
poisonous to the men doing the packing, while another 
may exhaust itself quickly and therefore be uneconomical. 

In justice to the manufacturers of these materials it 
may be stated that each mixture is suitable for certain 
classes of work. 

The compounds unsuitable for a clash gear in an auto- 
mobile transmission may be entirely satisfactory for the 
carburizing of ball and roller bearings. 



CARBURIZING MATERIAL 73 

- 

Materials and compounds are often poorly mixed, so 
that they are not homogeneous, with the result that work 
is penetrated unevenly, as shown in Figs. 36 and 37. 

The presence of free Cementite in quantity is due 
either to too high a temperature in carburizing or to the 
character of the carburizing compound. 

It gives rise to cracks and brittleness, and, further, 
brittleness is not limited to the case, but extends to and 
through the core. 

This is a cause of "freckled corners" and may be de- 
tected by the coarse fracture of a broken section. 



CHAPTER XII • 
HEAT TREATMENT AFTER CARBURIZING 

For some work after carburizing the box is emptied hot 
upon a sieve to separate the work from the compound 
and the pieces immediately quenched. This practice does 
not give the maximum strength and toughness. 

It is more advisable to allow the work to cool slowly 
in the pot, and when cold to remove it from the box, 
place it upon the floor of the furnace, heat to the hard- 
ening temperature and then quench. This will give 
a good case and a tough core, but in order to obtain a 
hard, refined case with a maximum strength and tough- 
ness, the work is heated to a temperature sufficiently 
high to refine the core and quenched, preferably in oil 
to avoid checking or cracking the case, and then heated 
again to the hardening temperature of the case and 
quenched in water. 

The object of the double quenching operation is to give 
the toughest possible core and the finest crystalline case, 
and a graduation of case into the core. 

The refining temperatures vary with the composition 
of the steel, and it is advisable to consult the specifications 
of the Society of Automotive Engineers as mentioned 
later. 

A carbon steel of 10- to 15-point carbon, carburized 
between the temperatures of 843 C. to 871 ° C. (1550 
Fahr. to 1600 Fahr.), and cooled in the pot and re- 
heated to the hardening temperature of the case and 
quenched will produce a tough core and fine, hard, com- 
pact case. The temperature in this instance is not 
high enough to coarsen the grain of the core. When 
carburizing at 954° C. (1750 Fahr.), the temperature 



HEAT TREATMENT AFTER CARBURIZING 75 

is above the critical range and the grain structure is 
coarsened, but can be broken up by a double heat treat- 
ment to a fairly fine grain. 

If strength and resistance to shock are of no import- 
ance and where surface hardness is the only requirement, 
pieces may be quenched directly from the carburizing 
boxes. The prolonged heating at the high carburizing 
temperature causes the steel to develop an exceedingly 
coarse grain, which, by this method of treatment, is 
retained in the finished product. 

Furthermore, during the quenching operation the hot 
compound is exposed to the air and considerable is lost 
by its combustion. Common practice, where time and 
cost permits, is to allow the work to cool in the boxes 
before removing and heat treating. 

Although where time does not permit the work to cool 
in the pots some concerns are quenching their work di- 
rectly from a carburizing temperature of 87 1° C. to 899 
C. (1600 Fahr. to 1650 Fahr.), and then reheating to 
the hardening point of the case and quenching. This 
first quenching should be done in a good quenching oil 
for the reason above noted. 



CHAPTER XIII 
THE HARDENING OF STEEL 

Steel in the Austenite stage, on cooling, reverts with 
greatest rapidity into the Martensite form, with an at- 
tendant increase in hardness and assumes a maximum 
volume. The increase of carbon and the presence of 
chrome, nickel, manganese, etc., retards this transforma- 
tion rate. (Twenty-five per cent, nickel preserves Austen- 
ite at atmospheric temperature.) 

To secure maximum hardness, the steel must be 
quenched with utmost rapidity in the coldest solution and 
most efficient conductor of heat. The resulting hardness 
varies directly with the efficiency of the bath as a con- 
ductor of heat, or rather as an abstractor of heat, and is 
directly a function of the time required tx> cool the steel 
to atmospheric temperature. 

Without the presence of a retarding alloy, chrome, for 
instance, it is difficult to commercially secure a Marten- 
sitic structure regularly, and when employing simple car- 
bon steels the resultant structure is most likely to be 
troostite or sorbite, which are softer structures. 

These things bring up some practical points in the 
quenching of steel. The careful operator may first adopt 
a furnace of the open-fired type, that heats as evenly as 
possible, and arrange it so that his work shall not be 
touched by flame or drafts, but for quantity production 
of fine tools, will doubtless install bath furnaces for the 
final heating before quenching with preheating furnaces 
nearby. He will, of necessity, adopt a pyrometer and 
keep it in order, for no eye is so trained that it can 
observe the niceties of temperature control required in 
fine and uniform hardening. Most important of all, he 



THE HARDENING OF STEEL 77 

will operate his furnace so that the temperature of the 
heating space never exceeds by more than about 25 ° 
Fahr. his desired quenching temperature, and even though 
this practice is slower he will be repaid by the uniformity 
of his product. 

Having provided means of even heating, so as to do 
away with cracking and warping as far as possible, he 
will secure a steel giving him the widest practicable range 
of control, the uniformity and nature of output consid- 
ered. The furnace, pyrometers and steel at hand, he 
will then select a quenching medium, oil for relatively soft 
work and intricate shapes, water for harder and so on, 
minding all the time the fact that the temperature of his 
bath and its constancy of composition are important fac- 
tors in making a good product. 

The care of the operator does not end here, for he 
knows that as uneven heating causes' a distortion of 
the work or rupture, so also will uneven quenching. If 
a ring of high carbon steel is quenched with its axis 
horizontal, so that one side turns to Martensite, while 
the other is still Austenite, the rapid increase of volume 
on the Martensite (cool) side will warp the piece five 
times as much out of round as if he had quenched it with 
the axis vertical. Then, again, if Martensite is aimed for, 
room for expansion must be allowed; this is greater in 
unalloyed than in some alloyed steels. Even if he uses 
a hardening fixture he will see that the work hits the 
water in a vertical position to prevent warping. 

Quenching should be done on an ascending heat to 
reduce the scale and the fire should not be an oxidizing 
one. 

The treatment must be adapted to the steel used and 
multiple treatments when within the critical range can 
only refine the structure. 

Low carbon steel or the soft backing of carburized steel, 
generally below .20 per cent, carbon, is only refined by 
heating to Acs for that steel 830 C. to 871 ° C. (1525 
Fahr. to 1600 Fahr.), and then uniformly cooling or 



78 STEEL AND ITS TREATMENT 

quenching. The case, however, represents a different 
steel, carrying possibly .80 to, 1 .30 per cent, carbon ; but 
as this has been obtained at 900 C. to 982 ° C. (1650 
Fahr. to 1800 Fahr.), the grain, already coarse, is 
slightly refined at 830 C. (1525 Fahr.), but still too 
coarse. This will be refined without affecting the size 
of grain of the core (see page 8, Fig 8) by quenching 
from AC3 for .80 to 1.10 per cent, carbon steel, or about 
760 ° C. (1400 Fahr.) and the resulting composite struc- 
ture is the finest the steel is capable of assuming. 

In quenching tools care will be necessary to have no 
sharp line of demarcation between the hardened and 
softer unquenched sections. 

Pyrometers are necessary in hardening high-speed steel 
at 1148 C. (2100 Fahr.) or above. 

In a general way the hardening temperatures are de- 
pendent only upon the carbon content, and alloys in the 
percentage usually contained in commercial tool steels 
do not materially affect the hardening temperatures, ex- 
cept in high speed steel. 

HARDENING TEMPERATURES FOR STEEL OF VARIOUS 
RANGES OF CARBON CONTENT. 

Up to .20% carbon use 871° to 899° C. (1600° to 1650° F.) 
From .20% to .35% C. use 843° to 871° C. (1550° to 1600° F.) 
From .35% to .50% C. use 815° to 843° C. (1500° to 1550° F.) 
From .50% to .70% C. use 787° to 815° C. (1450° to 1500° F.) 
From .70% to .90% C. use 760° to 787° C. (1400° to 1450° F.) 
.90% Cor over use 732° to 760° C. (1350° to 1400° F.) 

In order to give a hardening temperature for any 
definite steel, it would be necessary to know its com- 
position. 

The increase in hardness in the different grades of steel 
is governed by the carbon content, as well as the rate of 
cooling. The rate of cooling in turn is dependent on 
the size of the hardened piece of steel, as well as the 
nature of the quenching: medium. 

Whatever the quenching medium, whether brine, water 
or oil, its temperature should be kept low enough to pre- 



THE HARDENING OF STEEL 79 

vent adhesion of vapor bubbles to the quenched steel. In 
the selection of oils for the operation particular care 
should be taken to select one of uniform quenching speed, 
one which will not give off large amounts of gaseous 
vapors at comparatively low temperatures, and one which 
will not oxidize or thicken on continued use. 

From the above it is obvious that the hardening of steel 
consists in preventing the formation of soft Pearlite, and 
causing the formation and retention of the hard constitu- 
ent called Martensite. 

This hardening process, however, has its limitations 
when pieces of large cross sections are treated. It can 
readily be seen that the inside of a comparatively large 
piece will not cool as rapidly on quenching as the outside ; 
hence, the hardening effect is diminished and often 
eliminated. 

It is always better to harden work that has been pre- 
viously annealed, even tools and holder tools, because the 
working or forging strains liberated in the change from 
Pearlite to Martensite and Austenite may seriously warp 
or crack the steel ; if not in the fire, this cracking may 
take place some time later in use. Thus, mineral oils 
which consist of hydrocarbon compounds having different 
points of volatilization are quite unsuitable. 



CHAPTER XIV 
DRAWING OR TEMPERING 

We have mentioned the eagerness exhibited by the 
Austenite structure to transform itself into the original 
Pearlite through the Martensite, Troostite, Sorbite stages. 
It is the function of the quenching bath to trap the de- 
sired structure. If the quenching has proceeded with 
sufficient rapidity the steel retains the Martensite stage, 
but while here we have the greatest volume and hardness ; 
we also have the greatest brittleness. This is relieved 
by the process of drawing, or tempering. 

It is known that in hardened steel, when heated to 200 
C. to 400 C. (392 Fahr. to 752 ° Fahr.), another very 
slight temperature arrest occurs. This point is called 
Arc. At the lower temperature the Martensite of the 
hardened steel begins to change to the softer Troostite; 
then to Sorbite ; then at the higher temperature to soft 
Pearlite again without attendant increase in grain size. 

Fortunately, such low temperatures (about 200 C. or 
400 Fahr.) are controlled much more readily than the 
initial hardening heat, so that in this way the proper 
structure is readily obtained, a thing almost impossible 
to do at the original quenching. 

The increase in ductility and softening, however, is 
proportional to the temperature used in the drawing 
operation. For instance, heating hardened steel to a tem- 
perature of 134 C. (275 ° Fahr.), which is the tempera- 
ture at which drawing begins, would have very little ef- 
fect. The changes become more noticeable with in- 
creased temperature until the critical temperature is 
reached, when all the results obtained bv the hardening 



DRAWING OR TEMPERING 81 

operation are eliminated and the steel is in the same con- 
dition as it was previous to the hardening. 

The time of the drawing operation is largely depend- 
ent upon the size of the pieces, as well as the temperature. 
In other words, the same results can be obtained by draw- 
ing at a slightly lower temperature for a longer period of 
time, as at a higher temperature for a shorter period 
of time. 

Ordinarily this operation is carried on in heated oil or 
molten salt or lead-drawing furnaces. However, the old 
method of open furnace drawing for colors is still used 
for drawing the temper in tools extensively. The former 
tends to give the more accurate and uniform results, as 
they afford a means of more uniform heating and a better 
regulation of temperature. The selection of temperature 
and time for each individual type of parts can only be 
worked out by repeated trials until the desired results 
are obtained. When drawing by color it should be borne 
in mind, however, that results will vary with carbon 
content and condition of the steel. For instance, a piece 
of I per cent, (ioo point) carbon steel will blue quicker 
than a .50 per cent. (50 point) carbon steel, also a piece 
of hard steel of any carbon content will blue quicker 
than soft steel at the same heat. 



CHAPTER XV 

FURNACES FOR CASE-HARDENING 

In building or constructing a furnace for case-harden- 
ing the size of the work to be hardened should be the 
first consideration. It is far better to use a small furnace 
with a small box whenever possible. If the work varies 
in size, different sizes of furnaces may be used. Small 
furnaces require less fuel and small work must be placed 
in small boxes, as otherwise the pieces packed near the 
sides will be overheated, while those in the center will 
not reach the required temperature. 

Thick walls should be used to retain the heat. These 
walls should be supported by a substantial concrete 
foundation, so that they will retain their position and 
shape, even when subjected to a high heat. Sufficiently 
large flues should be provided to carry away the smoke 
and gases. 

The furnace should also be so constructed that as much 
as possible of the heat of the combustion gases may be 
extracted before they are discharged. The flues and all 
parts of the furnace should be easily accessible, and a 
door, the full width of the oven, should be provided, so 
that the tiles can be taken out and the flues cleaned. 
A pressure blower, with a light oil, should be used with 
all the pipes accessible and placed, preferably above the 
furnace. If, however, they are placed below ground they 
should be arranged in compartments which can be easily 
reached if repairs are required. 

The blower pipes should be run through the furnace so 
as to preheat the air used; if cold air is used directly it 
will reduce the heat in the furnace. The furnace fronts 
should be made in several parts to prevent cracking, with 



FURNACES FOR CASE-HARDENING 



83 




«H 


bC 


be 




£3 


s-l 


»lH 


S-l 




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3 




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84 STEEL AND ITS TREATMENT 

the door properly balanced and lined. A shelf should be 
provided, projecting at the front, for holding the boxes 
when they are taken out or put into the furnace. The 
smokestack should be made of sufficient height to produce 
a good draft. 

Furnaces 

In a carburizing furnace, it is perfectly satisfactory to 
have the flames enter the work chamber, in fact, an under- 
fired carburizing furnace does not stand up well. In an 
under-fired furnace such an intense heat is generated 
under the hearth that the hearth bricks are destroyed. 
The roof should be arched and the heating flames should 
enter on a tangent with the arch. It is also important 
that the arch and burner openings should be of sufficient 
height so that no flames will impinge directly against the 
pots. 

It is always well to operate furnaces under slight pres- 
sure (controlled by dampers), and with a rich atmosphere 
or flame. 

By the use of insulating brick in furnace construction 
heat losses by radiation are cut down. The wall thickness 
is not increased and the surrounding room is kept much 
cooler. 

Economy of radiation is effected by erecting in bat- 
teries-, which in the case of two furnaces, saves two radia- 
tion walls. (Fig. 38.) 

The furnace should not be heated too quickly, as this 
is apt to crack the brickwork. The cooling should also 
be done gradually. After the work has been taken out 
and the heat shut off for the day, all the dampers should 
be closed to hold the heat. In this way the furnace will 
cool slowly and crackings or bulging out of shape will be 
prevented. In addition, it will be easier to heat the fur- 
nace the next morning, as it will have retained some of 
the heat. 



FURNACES FOR CASE-HARDENING 



85 




86 



STEEL AND ITS TREATMENT 




FURNACES FOR CASE-HARDENING 87 

When work is to be annealed, it should be placed in the 
furnace after the work to be hardened has been removed, 
and then the furnace brought to the proper heat. 

The material to be anneaied can remain in the furnace 
until the next morning with the furnace closed and the 
burners turned off. 

The same general construction and operation applies 
to hardening furnaces of the muffle or semi-muffle type; 
however it is better on account of oxidation and scaling 
by combustion gases to underfire. 

For comfort of operation and best light conditions fur- 
naces should be placed at right angles to window side 
of room. (Figs. 39 and 40.) 



CHAPTER XVI 
HEATING 

The flame should be neutral or slightly rich in gas. 
This will prevent scaling- when heating for forging pur- 
poses, and surface decarbonization in annealing and heat 
treating. 

With a muffle furnace, of course, this precaution does 
not apply. All dies and tools of very fine edge should be 
heated in a mufBe furnace or packed in charcoal when 
heating for hardening. This method will give the hardest 
possible surface with the least possible oxidation. 

Great care should be exercised in the time required to 
bring the object to the right temperature. Heating should 
never be rapid ; the final approach to the correct tem- 
perature should be slow and uniform. 

The location of the pyrometer fire ends should be far 
from the live action of the flame, but should be placed 
either in the back or side of the furnace below the level 
of the arch or flue, where it will record the actual tem- 
perature of the furnace. 

Fire ends may be prDtected with steel or porcelain 
pipe, but it is advisable to use nickel chrome alloy tubes, 
as the carbon steel tubes oxidize very rapidly and the 
porcelain tubes are very brittle and easily broken. 

It is also advisable to have the fire ends loose at all 
times, so that when the protective case breaks the couple 
is less liable to be damaged and can be placed back in the 
furnace with a new case or pipe without calibration. 

A portable pyrometer should be used to check up heats 
frequently, as fire ends are liable to vary from time to 
time. 



CHAPTER XVII 
FUELS 

Gas, oil and coal are the fuels used for heating, al- 
though electricity is used to some extent with great ad- 
vantage. The first cost is, however, great, and in some 
localities the power cost makes it prohibitive. Oil is 
probably the most used. Coal is used in some districts 
on account of its low cost, but due to the difficulty of 
heat regulation and to the expense and annoyance of 
handling the ashes, etc., it is fast going out of general 
use for heat treating. 

It will be found cheaper when running heat treating 
furnaces nine or ten hours a day to keep them at a low 
heat during the night. Tests show that less fuel is burned 
this way than by shutting off the heat during the night, 
lighting in the morning, and forcing the heat. Also it 
eliminates the continual expansion and contraction that 
breaks a furnace down. 



CHAPTER XVIII 

QUENCHING 

The size of quenching tanks required for any particular 
class of work will depend upon the size of the pieces to 
be treated. .. 

It is advisable to have tanks of large capacity for use 
in quenching large pieces of steel. 

After the critical point of the various steels in use has 
been determined, the subject of next importance is the 
means of obtaining the proper hardness for the particu- 
lar purpose. 

When a piece of high carbon steel is heated through 
the critical range the carbon passes into the hardening 
form, and is retained in that form by proper cooling or 
quenching. Therefore, it is desirable to determine the 
speed at which the various liquids will cool the piece of 
steel and the uniformity in rate of quenching speed of the 
quenching mediums. 

Except in special cases, very high-carbon steels should 
not be quenched in water. Oil should invariably be used. 
Steel below 90-point carbon may be quenched in water. 

It is advisable to quench thin pieces in oil regardless 
of their carbon content. A piece of steel should be 
quenched in such a manner as to cause the least distor- 
tion. Where thick and heavy masses of metal are ad- 
jacent to thinner and smaller masses the hardener will 
have to use his judgment as to the best method of quench- 
ing. It is generally customary to quench the piece in 
such a way that the heavier parts come in contact with 
the quenching medium before the thinner parts. 

The selection of the quenching medium is at all times 
important. 



QUENCHING 



91 



The quenching mediums used most extensively are 
water, brine water and oil. 



PIPES THROUGH WHICH 
COLD WATER RUNS 







Fig. 41. 

Diagram showing Oil Quenching Tank and Cooling Tank fitted with 

cold-water coils. 

All hardening baths should be constructed with a view 
to keeping the temperatures of the bath constant at 
all times. 

Where water is used a slight circulation is necessary 
to keep the water from becoming stagnant, also for cool- 
ing purposes. Brine hardening is practiced very little and 
when done a small tank of brine is usually set in another 
tank of running water. For oil hardening, if the quantity 
of the work is small, the tank may also be set in a tank 
of circulating water. Where large amounts of work are 



92 STEEL AND ITS TREATMENT 

oil quenched, it is found necessary to cool the oil. This 
is done in four ways. An ammonia refrigerator machine 
where either the oil is circulated or cold brine is circu- 
lated in pipes through the oil. Second, circulating cold 
water through the oil tank or the oil through a cold water 
tank. (See Fig. 41.) Third, by flowing the oil over 
thin metal surfaces, exposing to the cooling effect of air; 
and, fourth, by bubbling of air through the oil. These last 
two in most oils are liable to cause gumming and oxida- 
tion. Also in the case of compressed air if the air comes 
in contact with the work while being quenched it is liable 
to cause soft spots. Where conditions permit, the am- 
monia refrigerating process is by far the most satisfactory. 

Fresh water in all parts of the country varies slightly 
from hard to soft water, depending upon the location. 

Brine, a mixture of water and common salt, is used in 
circulating systems or a small tank. Its use imparts 
greater hardness to steel than water, has a tendency to 
loosen the scale of the pieces when quenched and thus 
lessens the possibilities of soft spots. 

Oil for quenching should be one that possesses the 
greatest quenching speed. The oil should not decompose 
on continued use, nor absorb oxygen from the air and 
thicken up ; it should not undergo a fractional distillation, 
light ends going off and heavy ends remaining behind, 
and should not vary in its quenching speed. 

Water covered with a few inches of oil is used where 
the piece should be exceedingly hard, but quenching 
•directly in water would probably cause hardening cracks. 
The shock in quenching is not as severe as in the case of 
water and the steel obtains a hardness almost as great 
as that obtained from water. A quenching medium of 
this nature is kept cool by means of a water jacket. 

In order to successfully harden, one must study the 
various parts, their design and hardness desired. With 
the above quenching mediums a wide range of hardness 
can be secured and any condition satisfied if the bath is 
modified to suit the purpose. 



CHAPTER XIX 

MISCELLANEOUS HARDENING METHODS 

Heating in Lead 

Heating in lead is used extensively where only a slight 
variation in temperature is permissible. Lead has its 
disadvantages in that it is so dense as to necessitate hold- 
ing down the pieces in the lead by some mechanical 
means. The lead should be as pure as possible and espe- 
cially free from sulphur. Trouble is sometimes ex- 
perienced by the lead sticking to the work. This can be 
avoided by dipping the articles in a solution of cyanide of 
potassium and water — about one pound of the powdered 
cyanide to one gallon of boiling water. This should be 
used cold and the articles permitted to dry before plac- 
ing in the lead bath. The pieces should be left in the 
lead only long enough to heat them through. The pieces 
can be quenched in oil, water or brine, as preferred. 

To clean a lead pot it is advisable to add dry, common 
salt and stir thoroughly with the molten lead. All dirt 
and foreign matter will rise to the surface, which can be 
skimmed off with ease. 

Heating in Salt 

There is considerable difference of opinion regarding 
the method of heating in salt for hardening purposes. 
Barium chloride has been used quite extensively, and 
seems to work perfectly clean at first; but after having 
been used for some time it begins to pit the steel, which 
is probably due to the oxide dissolved in the metal salts. 
If the barium chloride is replaced it then works satis- 



94 STEEL AND ITS TREATMENT 

f actorily again. As long as this constant replacement goes 
on good results are obtained. 

There are other salts that seem to give satisfactory 
results. One of the large steel plants uses a mixture of 
calcium chloride and sodium chloride; about three parts 
of the former to one part of the latter. This combination 
melts at about 482 ° C. (900 Fahr.), and so is low enough 
to prevent the cooling effect of the steel from solidifying 
the bath. One advantage of the salt bath is that no bad 
results come from the material of the bath adhering to 
the object. When the latter is quenched the salt is 
solidified and cracks off. 

A mixture may be used consisting of calcium chloride 
or common salt and soda ash, or sal soda, in the propor- 
tion of one part of salt to two parts of soda ash if the 
latter be dry, or four parts of sal soda crystals. This 
mixture melts at 61 5 C, or 1140 Fahr., and may be 
used either by itself or as a covering on the lead bath. 
This will prevent oxidation of the lead and the steel, and 
the film formed on the surface of the steel prevents 
oxidation while it is being transported from the heating 
bath to the quenching bath, and assists in hardening, since 
the quenching bath will take hold of the clean surface 
quicker than an oxidized surface. 

Heating in Cyanide 

Cyanide of potassium is also used as a reheating 
medium. 

It prevents scaling and soft spots. 

It has a tendency to add an additional percentage of 
carbon to the outside surface of pieces when used as a 
reheating medium. 

Warping 

■ j ■ 

Warping may be caused by several factors, the two 
most important of which are : First, not having the steel 
in a proper condition of repose before it is hardened, and, 



MISCELLANEOUS HARDENING METHODS 95 

second, not putting the piece in the quenching bath prop- 
erly. As any operation of working steel is liable to set 
up internal strains it is always best after rolling, forging 
or machining steel to thoroughly anneal the piece before 
hardening it. This allows the piece to assume its natural 
state of repose. In the machining operation the roughing 
cuts should be taken off, the piece annealed, then the 
finishing cut should be given it and the piece hardened. 
This would also make the steel easier to machine, as the 
metal is more uniform and in its' softest state. 

There are several rules that can be followed in harden- 
ing a piece of steel to prevent warping, and these rules 
always assume that the piece has been properly annealed 
before starting the hardening operations. 

First — A piece should never be thrown into the bath, 
because in lying on the bottom it is apt to cool faster 
on one side than the other, and thus cause warping. 

Second — The piece should be agitated in the bath to 
destroy the coating of vapor which might prevent its 
cooling rapidly, and also to allow the bath to convey its 
acquired heat to the atmosphere. 

Third — Work should be quenched in the direction of 
its principal axis of symmetry, so that the liquid will 
cover the greatest possible surface at the instant of 
quenching. A gear wheel should be plunged perpendicu- 
lar to its plane, and a shaft vertically. 

Local Carburizing 

It is often desired to carburize only in certain places 
on the steel in question. There are several ways by which 
this may be done. First, by Japanning the part desired 
to be carburized and then copper-plating. The copper 
plate will prevent the penetration of the carbon. The 
Japan prevents copper from plating on the place where 
it is desired to carburize and will allow the carbon to 
pass through and into the steel. Second, by protecting 
the part not desired to be carburized by clay or a paint 
of water glass and kaolin. Third, by carburizing all 



96 STEEL AND ITS TREATMENT 

over, allowing enough stock at parts desired soft so that 
the carburized area may be machined off. We are in- 
debted to Mr. Frank Kaiser, Metallurgist for the Sullivan 
Machinery Co., Claremont, N. H., for the following: 

Selective; Hardening of Carburized Parts and 
Machining After Hardening 

"Occasionally a part is so designed that a portion of it 
is threaded and it is essential the threads be true and 
soft; the remainder of the part requiring hardness for 
wear. As a rule when a threaded part is carburized and 
hardened, it is warped and thrown out of centre with the 
ground surfaces of the rest of the piece. 

"To overcome this, the following method has been 
successful, although more time is required. 

"The part is machined for carburizing, leaving about 
%. inch of stock on section to be threaded. After car- 
burizing and cooling in the pot, this % inch is turned to 
within 1/64 inch of size. The part is then hardened by 
double treating, after which the hardened surfaces are 
ground. The end or section to be threaded is then turned 
to size (the remaining 1/64 inch), true to the ground sur- 
faces, and then threaded. When this ^ mcn is turned 
off the carburized zone is entirely machined off, leaving 
the soft core, and with careful selection of steel and con- 
trol of treatment, there is no difficulty in the final ma- 
chining operations. 

"Summarizing the operations they are as follows: 

"First — Machine for carburizing, leaving *4 mcn °f 
stock on section to be threaded. 

"Second— Carburize at 899 C. (1650 Fahr.) for 
depth of case desired, and cool in pot. 

"Third— Turn off all but 1/64 inch of the Y A inch 
stock left on section to be threaded. 

"Fourth— Heat to 815 to 871 C. (1550-1600 Fahr.), 
quench in water or oil. Reheat to 760 to 780 C. (1400- 
1440 Fahr.), quench in water or oil. 



MISCELLANEOUS HARDENING METHODS 97 

"Fifth — Grind hardened surfaces. 

"Sixth — Turn off remaining 1/64 inch true to ground 
surfaces. 

"Seventh — Thread. 

It is advisable to use .10 to .20 carbon steel for this 
class of work. 

Steel containing high carbon and high manganese is 
difficult to machine after heat treatment. 

Stylf, of Boxes 

After selecting the proper carburizing material the next 
important factor that enters into carburizing is the style 
of boxes or pots for packing the work to be carburized. 




Fig. 42. 
Fork for handling small carburizing boxes. 

A carburizing pot should be used that withstands the 
carburizing heat with the least loss in scaling and dis- 
tortion. 

The design or size of a suitable box for all purposes is 
impossible. The shape of the box should be suited to 
that of the work. 

The walls of the box should not exceed Yz inch nor be 
less than %. inch in thickness. Greater thickness would 
retard heating and thinner walls would cause scaling and 
cracking, thus permitting access of air. 

To insure more even and rapid heating the boxes should 
be supplied with legs at the bottom corners. 

All unnecessary weight in the boxes should be elimi- 
nated so as to save time and fuel in raising the tempera- 
ture of the furnace after loading. 
8 



98 



STEEL AND ITS TREATMENT 



The handling of the boxes when hot can be made easier 
by use of a suitable fork, as shown in Fig. 42, or a 
truck for handling heavier boxes, as shown in Fig. 43. 




Fig. 43. 
Truck for handling heavy carburizing boxes. 

Overhead track with trolley and chain hoist can be used 
in loading and unloading the furnaces. 

In motor car work the use of cylinder shaped boxes or 
pipes, placed in rows in the furnaces, filled with cam 
shafts and other parts of like nature that require uniform 
penetration is a common practice. 

The study of suitable boxes, pots or pipe for any class 
of work is time well spent. 



MISCELLANEOUS HARDENING METHODS 9\) 

Pots with cored center are used for gears, ball and 
roller bearings and small parts to obtain the most uniform 
rate of penetration, as shown in Figs. 44 and 45. 

The pieces should be packed at least % inch apart and 
Yz inch from the sides of the carburizing pot. It is ad- 
visable to place 1 inch of carburizing material on top of 
the work under the lid of the pot to allow for shrinkage 
of the carburizing material. 

A lid of the same composition as the carburizing box 
is placed upon the box and the edges luted with a mix- 
ture of 45 per cent, fire clay, 45 per cent, sand and 10 
per cent. salt. 

The following experiments were conducted to determine 
the comparative life of various carburizing pots used for 
carburizing purposes. 

The pots were of the same size and thickness of metal, 
and used at a temperature of 954° C. (1750 Fahr.). 

Several pots of the same composition were obtained 
from various manufacturers. 

Material Life 

Malleable Iron 465 hrs. 

Malleable Iron 415 " 

Alloy Steel, Ni-Cr 517 " 

Cast Steel 552 " 

Cast Steel 460 " 

Puddled Iron 475 " 

Wrought Steel 386 " 

Cast Iron 169 " 

Cast Iron 75 " 

There is a Nichrome carburizing pot on the market 
which is under test to determine its life, and at the time 
of this writing it has been subjected to a heat of (1750 
Fahr.) for 7,000 hours without the loss of weight. 

Nichrome pots must last many times as long as mal- 
leable iron pots to be more economical ; but judging from 
the life of Nichrome pyrometer protection tubes in car- 
burizing fires these pots should prove more efficient. 

These pots should undoubtedly produce more uniform 
results, inasmuch as the thickness of the sides of the pots 



100 



STEEL AND ITS TREATMENT 




Fig. 44. 

Packing pots at the Timken Roller Bearing Co., Canton, O^io, one of 

the largest users of carburizing material in the United States. 




Fig. 45. 
Unpotting the parts at Timken Roller Bearing Co., Canton, Ohio. 



MISCELLANEOUS HARDENING METHODS 101 

. 

will not diminish as rapidly as the usual iron pots, thereby 
producing more uniform rate of heating through the same. 
Although concerns continuously changing the sizes and 
shapes of their carburizing work could not use these pots 
economically. 

Carburizing Materials 

All carburizing material should be kept clean. The 
time is well spent in removing iron scale and fire clay 
from the carburizing material, as these foreign materials 
cause soft spots. 

The carburizing material should be kept dry, as moist- 
ure tends to pit the work and causes soft spots. 

Pipes of suitable diameters can be used for carburizing 
cam-shafts, spindles, etc. 

The case of all work to be ground after carburizing 
should possess a carbon content above 90 point, otherwise 
it will be ground below the carbon point which gives the 
hardest possible surface. This is often the cause of soft 
spots in carburizing. 

Calibration of Pyrometers 

The calibration of a pyrometer may be accomplished 
readily and accurately without the use of an extensive 
laboratory equipment. The easiest and most convenient 
method is that based upon determining the melting point 
of common table salt (sodium chloride). Chemically 
pure salt, which is neither expensive nor difficult to pro- 
cure, should be used where accuracy is desired. The salt 
is melted in a clean crucible of fire clay, iron or nickel, 
either in a furnace or over a forge fire, and then further 
heated until a temperature of about 875 ° to 900 C. 
(1607 to 1652 Fahr.) is attained. It is essential that 
this crucible be clean, because a slight mixture of a for- 
eign substance might noticeably lower or raise the melting 
point. 

The thermocouple to be calibrated is then removed from 
its protecting tube and its hot end is immersed in the salt 



102 STEEL AND ITS TREATMENT 

bath. When this end has reached the temperature of the 
bath the crucible is removed from the source of heat and 
allowed to cool, and while cooling readings are taken 
every ten seconds on the millivoltmeter. 

A curve is then plotted by using time and temperature 
as co-ordinates, and the temperature of the melting point 
of salt, as indicated by this particular thermocouple, is 
noted — at the point, namely, where the temperature of 
the bath remains temporarily constant while the salt is 
freezing. The length of time during which the tempera- 
ture is stationary depends on the size of the bath and the 
rate of cooling, and is not a factor in the calibration. 
The true melting point of salt is 8oi° C. (1474 Fahr.), 
and the needed correction for the instrument under ob- 
servation can be readily applied. 



MISCELLANEOUS HARDENING METHODS 103 
TABLE NO. Ill 

TEMPERING HEATS OF STEEL, SHOWING COLORS CORRE- 
SPONDING TO DIFFERENT TEMPERATURES 

215.6° C. 420° F Very faint yellow 

221.1° C. 430° F '. Very pale yellow 

•226.7° C. 440° F Light yellow 

232.2° C. 450° F Pale straw yellow 

237.8° C. 460° F Deep straw yellow 

243.3° C. 470° F Dark yellow— Straw yellow 

248.9° C. 480° F Deep straw 

254.4° C. 490° F Yellow brown 

260.0° C. 500° F Brown yellow 

265.6° C. 510° F Spotted red brown 

271.1° C. 520° F Brown purple 

276.7° C. 530° F Light purple 

282.2° C. 540° F Full purple 

287.8° C. 550° F Dark purple 

293.3° C. 560° F Full blue 

298.9° C. 570° F. Dark blue 

315.6° C. 600° F Very dark blue 

400° C. 752° F Red— Visible in the dark 

474° C. 885° F Red— Visible at twilight 

525° C. 975° F Red— Visible at daylight 

581° C. 1077° F Red— Visible at sunlight 

700° C. 1292° F Dark red 

800° C. 1472° F Dull cherry red 

900° C. 1652° F Cherry red 

1000° C. 1832° F Bright cherry red 

1100° C. 2012° F Orange red 

1200° C. 2192° F Orange yellow 

1300° C. 2372° F Yellow white 

1400° C. 2552° F White; Welding 

1500° C. 2732° F Brilliant white 

1600° C. 2912° F Bluish white 



104 STEEL AND ITS TREATMENT 

To Reduce the Degrees oe a Fahrenheit Thermom- 
eter to Those of Reaumer and the Centi- 
grade, and Contrariwise 

Fahrenheit to Reaumer. — // above the freezing point. — ■ 
Subtract 32 from the number of degrees ; multiply the re- 
mainder by 4, and divide the product by 9. 

Thus, 212 — 32° = i8o°, and i8o°X4-^9=8o°. 

// below the freezing point. — Add 32 to the number 
of degrees ; multiply the sum by 4, and divide the product 
by 9. 

Thus, 40 +32°=72°, and 72° X4=9=— 32°. 

Reaumer to Fahrenheit. — Multiply the number of de- 
grees by 9, and divide the product by 4. Then when they 
are above the freezing point, add 32 to the quotient, and 
when they are below, subtract 32. 
. : Thus, 8o°X9-M-=i8o, and 180+32=212°. 
— 32°X9-^-4=7 2 , and 72—32=40°. 
,. Fahrenheit to Centigrade. — If above the freezing point. 
—Subtract 32 from the number of degrees ; multiply the 
remainder by 5, and divide the product by 9. 

Thus, 2i2°— 32°X5^-9=i8oX5^-9==ioo°. 

If below the freezing point. —Add 32 to the number of 
degrees; multiply the sum by 5, and divide the product 
by 9. 

'.Thus, — 40 +32X5-^9=72X5-S-9=— 40°. 

Centigrade to Fahrenheit. — Multiply the number of 
degrees by 9, and divide the product by 5. Then, when 
they are above the freezing point, add 32 to the quotient, 
and when they are below, subtract 32. 

Thus, ioo°X9^-5=i8o, and 180+32=212°. 
" — io°X9^5=i8, and 18—32=14°. 

Reaumer to Centigrade. — Multiply by 5 and divide by 
4 — thus: 8o°X 5=400, and 400^-4=100. 

Centigrade to Reaumer. — Multiply by 4 and divide by 5. 

Thus ioo°X4=400, and 400^-5=80°. 



MISCELLANEOUS HARDENING METHODS 105 



TABLE No. IV 

Equivalent of Degrees Centigrade in Fahrenheit 



Degrees 






















Centi- 


^0 


10 


20 


30 


40 


50 


60 


70 


80 


90 


grade 






















I 


Degrees Fahrenheit 





32 


50 


68 


86 


104 


122 


140 


158 


176 


194 


100 


212 


230 


248 


266 


284 


302 


320 


338 


356 


374 


200 


392 


410 


428 


446 


464 


482 


500 


518 


536 


554 


300 


572 


590 


608 


626 


644 


662 


680 


698 


716 


734 


400 


752 


770 


788 


806 


824 


842 


860 


878 


896 


914 


500 


932 


950 


968 


986 


1004 


1022 


1040 


1057 


1076 


1094 


600 


1112 


1130 


1148 


1166 


1184 


1202 


1220 


1237 


1256 


1274 


700 


1292 


1310 


1328 


1345 


1364 


1382 


1400 


1418 


1436 


1454 


800 


1472 


1490 


1508 


1526 


1544 


1562 


1580 


1598 


1616 


1634 


900 


1652 


1670 


1688 


1706 


1724 


1742 


1760 


1778 


1796 


1814 


1000 


1830 


1850 


1868 


1886 


1904 


1922 


1940 


1958 


1976 


1994 


1100 


2012 


2030 


2048 


2066 


2084 


2102 


2120 


2138 


2156 


2174 


1200 


2192 


2210 


2228 


2246 


2264 


2282 


2300 


2318 


2336 


2354 


1300 


2372 


2390 


2408 


2426 


2444 


2462 


2480 2498 


2516 


2534 


1400 


2552 


2570 


2588 


2606 


2624 


2642 


2660 2678 


2696 


2714 


1500 


2732 


2750 


2768 


2786 


2804 


2822 


2840 2858 


2876 


2894 


1600 


2912 


2930 


2948 


2966 


2984 


3002 


3020 3038 


3056 


3074 


1700 


3092 


3110 


3128 


3146 


3164 


3182 


3200 ! 3218 


3236 


3254 


1800 


3272 


3290 


3308 


3326 


3344 


3362 


3380 


3398 


3416 


3434 


1900 


3452 


3470 


3488 


3506 


3524 


3542 


3560 


3578 


3596 


3614 


2000 


3632 


3650 


3668 


3686 


3704 


3722 


3740 


3758 


3776 


3794 



SPECIFICATIONS FOR STEEL 

AMERICAN SOCIETY 
OF AUTOMOTIVE ENGINEERS 



SPECIFICATIONS FOR STEEL 

AMERICAN SOCIETY OF AUTOMOTIVE 

ENGINEERS 

SEVENTH REPORT OF IRON AND STEEL DIVISION 

SPECIFICATION NUMBERS 

A numeral index system has been adopted in the numbering of 
the metal specifications contained in this report. This system 
renders it possible to employ specification numerals on shop draw- 
ings and blue prints, that are partially descriptive of the quality 
of material covered by such number. The first figure indicates 
the class to which the steel belongs ; thus J indicates a carbon 
steel, 2 nickel, 3 nickel chromium, etc. In the case of the alloy 
steels, the second figure generally indicates the approximate per- 
centage of the predominant alloying element. The last two or 
three figures indicate the average carbon content in "points," or 
hundredths of one per cent. Thus 2340 indicates a nickel steel 
with approximately 3 per cent, nickel (3.25% — 3.75%) and 0.40 
per cent, carbon (.35% — .45%), and 51 120 indicates a chromium 
steel with about 1 per cent, chromium (.90% — 1.10%) and 1.20 
per cent, carbon (1.10%— 1.30%). 

The basic numerals for the various qualities of steels herein 
specified follow : 

Carbon steels 1 

Nickel steels 2 

Nickel chromium steels 3 

Chromium steels 5 

Chromium vanadium steels 6 

Silico-manganese steels 9 

The specification for malleable iron has not been assigned a 
basic numeral in these specifications. 



110 STEEL AND ITS TREATMENT 

SPECIFICATIONS FOR STEEL 
MANUFACTURE AND COMPOSITION 

These steels may be of open-hearth, crucible or electric furnace 
manufacture, and must be homogeneous, sound and free from 
physical defects, such as pipes, seams, heavy scale or scabs and 
surface and internal defects visible to the naked eye. 

These steels will be purchased on the basis of chemical analy- 
sis. The specifications indicate the desired chemical composition. 
Any shipments not conforming to these specifications after careful 
check analysis may be rejected. 

METHODS FOR SAMPLING 

Materials to be sampled shall be considered under three classes, 
namely : 

1. Wire, tubing, sheet and rod metal less than 1% inch in size 
shall be sampled across or through the entire section. 

2. Forgings or pieces of irregular shape shall be sampled by 
drilling or cutting at thickest and thinnest sections, or through or 
across entire section.* 

3. Bars and billets or other shapes above V/i inch thick shall 
be drilled at half radius, or half-way between center and exterior 
surfaces. 



* In drop forgings changes of carbon may be looked for in the 
outer V 8 inch of metal. 



S. A. E. SPECIFICATIONS 111 

CARBON STEELS 

SPECIFICATION NO. 1010 

Carbon 05% to .15% ( .10% desired) 

Manganese 30% to .60% ( .45% desired) 

Phosphorus, not to exceed.... .045% 

*Sulphur, not to exceed .05% 

SPECIFICATION NO. 1020 

Carbon 15% to .25% ( .20% desired) 

Manganese , 30% to .60% ( .45% desired) 

Phosphorus, not to exceed. . . . .045% 

*Sulphur, not to exceed .05% 

SPECIFICATION NO. 1025 

Carbon 20% to .30% ( .25% desired) 

Manganese 50% to .80% ( .65% desired) 

Phosphorus, not to exceed. . . . .045% 

*Sulphur, not to exceed .05% 

SPECIFICATION NO. 1035 

Carbon 30% to .40% ( .35% desired) 

Manganese 50% to .80% ( .65% desired) 

Phosphorus, not to exceed.... .045% 

* Sulphur, not to exceed .05% 

SPECIFICATION NO. 1045 

Carbon .' 40% to .50% ( .45% desired) 

Manganese 50% to .80% ( .65% desired) 

Phosphorus, not to exceed. . . . .045% 

^Sulphur, not to exceed .05% 

SPECIFICATION NO. 1095 

Carbon 90% to 1.05% ( .95% desired) 

Manganese 25% to .50% ( .35% desired) 

Phosphorus, not to exceed.... .04% 

* Sulphur, not to exceed .05% 

* See note on page 120. 



112 STEEL AND ITS TREATMENT 

SCREW STOCK 

SPECIFICATION NO. 1114 
Carbon - .08% to .20% 



Manganese 30% to .ouyo 

Phosphorus, not to exceed .12% 

♦Sulphur 06% to .12% 

STEEL CASTINGS 

SPECIFICATION NO. 1235 

Carbon As required for physical properties 

Phosphorus, not to exceed .05% 

*Sulphur, not to exceed .05% 

Note. — See "Notes and Instructions." 

NICKEL STEELS 

SPECIFICATION NO. 2315 

Carbon .10% to .20% ( .15% desired) 

Manganese 50% to .80% ( .65% desired) 

Phosphorus, not to exceed .04% 

♦Sulphur, not to exceed .05% 

Nickel 3.25% to 3.75% (3.50% desired) 

SPECIFICATION NO. 2320 

Carbon 15% to .25% ( .20% desired) 

Manganese 50% to .80% ( .65% desired) 

Phosphorus, not to exceed.... .04% 

♦Sulphur, not to exceed .045% 

Nickel 3.25% to 3.75% (3.50% desired) 

SPECIFICATION NO. 2330 

Carbon 25% to .35% ( .30% desired) 

Manganese 50% to .80% ( .65% desired) 

Phosphorus, not to exceed .04% 

♦Sulphur, not to exceed .045% 

Nickel 3.25% to 3.75% (3.50% desired) 

* See note on page 120. 



S. A. E. SPECIFICATIONS 113 

SPECIFICATION NO. 2335 

Carbon 30% to .40% ( .35% desired) 

Manganese 50% to .80'% ( .65% desired) 

Phosphorus, not to exceed .... .04% 

♦Sulphur, not to exceed....... .045% 

Nickel 3.25% to 3.75% (3.50% desired ) 

SPECIFICATION NO. 2340 

Carbon 35% to .45% ( .40% desired) 

Manganese 50% to .80'% ( .65% desired) 

Phosphorus, not to exceed.... .04% 

♦Sulphur, not to exceed .045% 

Nickel 3.25% to 3.75% (3.50% desired) 

SPECIFICATION NO. 2345 

Carbon 40% to .50% ( .45% desired) 

Manganese 50% to .80% ( .65% desired) 

Phosphorous, not to exceed... .04% 

♦Sulphur, not to exceed .045% 

Nickel 3.25% to 3.75% (3.50% desired) 

NICKEL CHROMIUM STEELS 

SPECIFICATION NO. 3120 

Carbon 15% to .25% ( .20% desired) 

Manganese 50% to .80% ( .65% desired) 

Phosphorus, not to exceed.... .04% 

♦Sulphur, not to exceed .045% 

Nickel 1.00% to 1.50% (1.25% desired) 

Chromium 45% to ,75%f ( .60% desired) 

* See note on page 120. 

f Another grade of this type of steel is available with chromium 
content of .15 per cent, to .45 per cent. Its physical properties are 
somewhat lower than those of the grade with chromium content indi- 
cated in specifications Nos. 3120, 3125, 3130, 3135 and 3140. 

9 



114 



STEEL AND ITS TREATMENT 



SPECIFICATION NO. 3125 

Carbon . . 20% to .30% 

Manganese .50% to .80% 

Phosphorus, not to exceed .04% 

*Sulphur, not to exceed 



.045% 

Nickel 1.00% to 1.50% 

Chromium 45% to .75% t 

SPECIFICATION NO. 3130 

Carbon 25% to .35% 

Manganese .50% to .80% 

Phosphorus, not to exceed .04% 

*Sulphur, not to exceed .045% 

Nickel 1.00% to 1.50% 

Chromium 45% to .75% f 



SPECIFICATION NO. 3135 

Carbon 30% to .40% 

Manganese 50% to .80% 

Phosphorus, not to exceed .04% 

*Sulphur, not to exceed .045% 

Nickel 1.00% to 1 50% 

Chromium 45% to .75%t 

SPECIFICATION NO. 3140 

Carbon : 35% to .45% 

Manganese 50% to .80% 

Phosphorus, not to exceed .04% 

*Sulphur, not to exceed .045% 

Nickel 1.00% to 1.50% 

Chromium 45% to .75% t 



.25% desired) 
.65% desired) 



1.25% desired) 
.60% desired) 



.30% desired) 
.65% desired) 



1.25% desired) 
.60% desired) 



.35% desired) 
Jo desired) 



1.25% desired) 
.60% desired) 



.40% desired) 
Jo desired) 



1.25% desired) 
.60% desired) 



* See note on page 120. 

f Another grade of this type of steel is available with chromium 
content of .15 per cent, to .45 per cent. Its physical properties are 
somewhat lower than those of the grade with chromium content indi- 
cated in specifications Nos. 3120, 3125, 3130, 3135 and 3140. 



S. A. E. SPECIFICATIONS 



115 



SPECIFICATION NO 

Carbon 15% to 

Manganese 30% to 

Phosphorus, not to exceed.... 

*Sulphur, not to exceed 

Nickel 1.50% to 

Chromium „ .90% to 

SPECIFICATION NO 

Carbon 25% to 

Manganese „ . . . .30% to 

P'hosphorus, not to exceed 

*Sulphur, not to exceed 

Nickel 1.50% to 

Chromium 90% to 

SPECIFICATION NO 

Carbon 35% to 

Manganese 30% to 

Phosphorus, not to exceed.... 

*Sulphur, riot to exceed 

Nickel 1.50% to 

Chromium 90% to 

SPECIFICATION NO 

Carbon 45% to 

Manganese 30% to 

P'hosphorus, not to exceed.... 

*Sulphur, not to exceed 

Nickel 1.50% to 

Chromium 90% to 

SPECIFICATION NO. 

Carbon 10% to 

Manganese 45% to 

Phosphorus, not to exceed.... 

*Sulphur, not to exceed 

Nickel 2.75% to 

Chromium 60% to 

* See note on page 120. 



. 3220 






.25% ( 


; .20% 


desired) 


.60% ( 


: .45% 


desired) 


.04% 






.04% 






2.00% ( 


1.75% 


desired) 


1.25% ( 


:i.io% 


desired) 


. 3230 






.35% ( 


: .30% 


desired) 


.60% 1 


: .45% 


desired) 


.04% 






.04% 






2.00% < 


:i.75% 


desired) 


1.25% < 


;i.io% 


desired) 


. 3240 






.45% I 


: .40% 


desired) 


.60% 


: .45% 


desired) 


.04% 






.04% 






2.00% < 


[1.75% 


desired) 


1.25% ( 


[1.10% 


desired) 


. 3250 






.55% ( 


: .50% 


desired) 


.60% 1 


: .45% 


desired) 


.04% 






.04% 






2.00% ( 


:i.75% 


desired) 


1.25% ( 


:i.io% 


desired) 


X3315 






.20% < 


: .15% 


desired) 


.75% ( 


; .60% 


desired) 


.04% 






.04% 






3.25% ( 


3.00% 


desired) 


.95% < 


: .80% 


desired) 



116 



STEEL AND ITS TREATMENT 



SPECIFICATION NO. 

Carbon 30% to 

Manganese .45% to 

Phosphorus, not to exceed../. 

*Sulphur, rot to exceed 

Nickel 2.75% to 

Chromium 60% to 

SPECIFICATION NO. 

Carbon 45% to 

Manganese 45% to 

Phosphorus, not to exceed.... 

*Sulphur, not to exceed 

Nickel , . . 2.75% to 

Chromium 60% to 

SPECIFICATION NO 

Carbon 15% to 

Manganese 30% to 

Phosphorus, not to exceed.... 

*Sulphur, not to exceed 

Nickel 3.25% to 

Chromium 1.25% to 

SPECIFICATION NO 

Carbon 25% to 

Manganese 30% to 

Phosphorus, not to exceed.... 

*Sulphur, not to exceed 

Nickel 3.25% to 

Chromium 1.25% to 

SPECIFICATION NO 

Carbon 35% to 

Manganese , 30% to 

Phosphorus, not to exceed .... 

*Sulphur, not to exceed 

Nickel 3.25% to 

Chromium 1 .25% to 

* See note on page 120. 



X3335 






.40% 


( .35% 


desired) 


.75% 


( .60% 


desired) 


.04% 






.04% 






3.25% 


;3.oo% 


desired) 


.95% 


( .80% 


desired) 


X3350 






.55% 


: .50% 


desired) 


.75% 


{ .60% 


desired) 


.04% 






.04% 






3.25% I 


:3.oo% 


desired) 


.95% 


: .80% 


desired) 


. 3320 






.25% 1 


; .20% 


desired) 


.60% I 


: .45% 


desired) 


.04% 






.04% 






3.75% 1 


;3.50% 


desired) 


1.75% ( 


:i.5o% 


desired) 


. 3330 






.35% ( 


: .30% 


desired) 


.60% ( 


: .45% 


desired) 


.04% 






.04% 






3.75% ( 


'3.50% 


desired) 


1.75% ( 


1.50% 


desired) 


. 3340 






.45% ( 


' .40% 


desired) 


.60% ( 


; .45% 


desired) 


.04% 






.04% 






3.75% ( 


3.50% 


desired) 


1.75% ( 


1.50% 


desired) 



S. A. E. SPECIFICATIONS 



117 



CHROMIUM STEELS 

SPECIFICATION NO. 5120 

Carbon 15% to .25% 

Manganese 1 

Phosphorus, not to exceed.... .04% 

*Sulphur, not to exceed .045% 

Chromium 05% to .85% 

SPECIFICATION NO. 5140 

Carbon 35% to .45% 

Manganese t 

Phosphorus, not to exceed.... .04% 

*Sulphur, not to exceed .045% 

Chromium 65% to .85% 



SPECIFICATION NO. 5165 

Carbon 60% to .70% 

Manganese J 

Phosphorus, not to exceed.... .04% 

*Sulphur, not to exceed .045% 

Chromium 65% to .85% 

SPECIFICATION NO. 5195 

Carbon 90% to 1.05% 

Manganese 20% to .45% 

Phosphorus, not to exceed.... .03% 

*Sulphur, not to exceed .03% 

Chromium 90% to 1.10% 

SPECIFICATION NO. 51120 

Carbon 110% to 1.30% 

Manganese 20% to .45% 

Phosphorus, not to exceed.... .03% 

*Sulphur, not to exceed .03% 

Chromium 90% to 1.10% (1.00% desired) 

* See note ou page 120. 

t Two types of steel are available in this class, viz., one with man- 
ganese .25 to .50 per cent. (.35 per cent, desired), and silicon not 
over .20 per cent. ; the other with manganese .60 to .80 per cent. (.70 
per cent, desired), and silicon .15 to .50 per cent. 



.20% desired) 

.75% desired) 

.40% desired) 

.75% desired) 

.65% desired) 

.75% desired) 



.95% desired) 
.35% desired) 



1.00% desired) 



1.20% desired) 
.35% desired) 



118 STEEL AND ITS TREATMENT 

SPECIFICATION NO. 5295 

Carbon .90% to 1.05% ( .95% desired) 

Manganese 20% to .45% ( .35% desired) 

Phosphorus, not to exceed...-. .03% 

*Sulphur, not to exceed .03% 

Chromium 1.10% to 1.30% (1.20% desired) 

SPECIFICATION NO. 52120 

Carbon 1.10% to 1.30% (1.20% desired) 

Manganese 20% to .45% ( .35% desired) 

Phosphorus, not to exceed .03% 

*Sulphur, not to exceed...... .€3% 

Chromium 1.10% to 1.30% (1.20% desired) 

CHROMIUM VANADIUM STEELS 

SPECIFICATION NO. 6120 

Carbon 15% to .25% ( .20% desired) 

Manganese 50% to .80% ( .65% desired) 

Phosphorus, not to exceed .04% 

*Sulphur, not to exceed .04% 

Chromium 80% to 1.10% ( .95% desired) 

Vanadium, not less than .15% ( .18% desired) 

SPECIFICATION NO. 6125 

Carbon 20% to .30% ( .25% desired) 

Manganese 50% to .80% ( .65% desired) 

Phosphorus, not to exceed .04% 

*Sulphur, not to exceed .04% 

Chromium 80% to 1.10% ( .95% desired) 

Vanadium, not less than .15% ( .18% desired) 

SPECIFICATION NO. 6130 

Carbon 25% to .35% ( .30% desired) 

Manganese 50% to .80% ( .65% desired) 

Phosphorus, not to exceed .04% 

*Sulphur, not to exceed .04% 

Chromium 80% to 1.10% ( .95% desired) 

Vanadium, not less than * .15% ( .18% desired) 

* See note on page 120. 



S. A. E. SPECIFICATIONS 



119 



SPECIFICATION NO 

Carbon 30% to 

Manganese .50% to 

Phosphorus, not to exceed.... 

*Sulphur, not to exceed 

Chromium 80% to 

Vanadium, not less than .. 

SPECIFICATION NO 

Carbon 35% to 

Manganese 50% to 

Phosphorus, not to exceed 

*Sulphur, not to exceed 

Chromium 80% to 

Vanadium, not less than 

SPECIFICATION NO 

Carbon 40% to 

Manganese 50% to 

Phosphorus, not to exceed 

*Sulphur, not to exceed 

Chromium 80% to 

Vanadium, not less than 

SPECIFICATION NO 

Carbon 45% to 

Manganese 50% to 

Phosphorus, not to exceed.... 

* Sulphur, not to exceed 

Chromium 80% to 

Vanadium, not less than 

SPECIFICATION NO. 
Carbon .90% to 

Manganese 20% to 

Phosphorus, not to exceed 

*Sulphur, not to exceed 

Chromium 80% to 

Vanadium, not less than 

* See note on page 120. 



. 6135 






.40% ( 


; .35% 


desired) 


.80% ( 


; .65% 


desired) 


.04% 






.04% 






1.10% 1 


: .95% 


desired) 


.15% ( 


; .18% 


desired) 


. 6140 






.45% 


: .40% 


desired) 


.80% < 


: .65% 


desired) 


.04% 






.04% 






1.10% 


; .95% 


desired) 


.15% 


; .18% 


desired) 


. 6145 






.50% 


; .45% 


desired) 


.80% 


[ .65% 


desired) 


.04% 






.04% 






1.10% 


[ .95% 


desired) 


.15% < 


; .18% 


desired) 


. 6150 






.55% I 


: .50% 


desired) 


.80% { 


: .65% 


desired) 


.04% 






.04% 






1.10% ( 


: .95% 


desired) 


.15% ( 


: .18% 


desired) 


. 6195 






1.05% ( 


: .95% 


desired) 


.45% ( 


' .35% 


desired) 


.03% 






.03% 






1.10% ( 


.95% 


desired) 


.15% ( 


.18% 


desired) 



120 STEEL AND ITS TREATMENT 

SILICO-MANGANESE STEEL 

SPECIFICATION NO. 9250 

Carbon . . . .45% to .55% ( .50% desired) 

Manganese 60% to .80% ( .70% desired) 

Phosphorus, not to exceed .045%f 

*Sulphur, not to exceed .045% 

Silicon 1.80% to 2.10% (1.95% desired) 

SPECIFICATION NO. 9260 

Carbon 55% to .65% ( .60% desired) 

Manganese 50% to .70% ( .60% desired) 

Phosphorus, not to exceed .045%t 

*Sulphur, not to exceed . . .045% 

Silicon 1.50% to 1.80% (1.65% desired) 

MALLEABLE IRON 

Manganese 30% to .70% 

Phosphorus, not to exceed.... .20% 

*Sulphur, not to exceed .06% 

.Silicon, not to exceed 1.00% 



* Recognizing the wide variance in methods used for the determina- 
tion of sulphur, the final reference method shall be the gravimetric 
(aqua regia) method, by oxidation. 

t Steel made by the acid process may contain maximum .05 per cent, 
phosphorus. 



REVISED NOTES AND INSTRUCTIONS 

REFERRING TO MATERIALS 

SPECIFIED 

REGARDING NOTES AND INSTRUCTIONS 

The notes and instructions following the chemical specifications 
are not to be considered in any way a part of these specifications. 
They are added solely for the information of the user of the 
steels and for the guidance of the purchaser in the selection of 
proper steels for his different purposes. They should not be in- 
corporated in the specification when ordering steel. This is espe- 
cially true of the "Physical Characteristics." Where possible, 
specific data are given on the physical properties which can be 
expected with the most widely used heat treatments. 

REMARKS CONCERNING GENERAL PHYSICAL 
PROPERTY DATA 

The materials specified in detail as S. A. E. steels include the 
most important ones available to the builder of automobiles. 

The results of physical tests, whether tension tests or other- 
wise, are largely dependent upon the mass and form of the speci- 
men tested. This is particularly true of heat-treated steels. For 
the foregoing reason all results of physical tests are comparative, 
and in order to make the comparison a proper one a uniform test 
specimen must be used. 

The committee therefore decided that recommended practice 
should be the use of the S. A. E. standard test specimen, this 
specimen to be treated approximately in its finished form, leaving 
only sufficient stock for finish grinding after the treatment is 
completed, say .020 inch on the diameter. 

The figures for physical characteristics given for all steels fol- 
lowing Specification No. 1045 refer to those obtained on speci- 



122 STEEL AND ITS TREATMENT 

mens prepared from sections common in automobile use, that is, 
bars from 1 inch round up to 1^ inches round. 

The yield point is under control in two ways — by choice of 
quenching medium (oil, water or brine), and by varying the final 
drawing temperature. In the interpretation of the physical char- 
acteristic figures it must be remembered that only the minimum 
figures as to toughness (i. e., reduction and elongation) may be 
expected with the highest degree of strength (i. e., yield point) ; 
and, conversely, that the highest degree of toughness may be ex- 
pected with the lowest yield point. This remark applies to all 
heat-treated steels. It would be manifestly impossible to obtain 
the highest percentage of elongation and the highest yield point on 
the same specimen. 

The yield point is specified rather than the elastic limit. The 
yield point is measured by the drop of the testing machine beam, 
and furnishes the most ready and widely used measure of the 
so-called elastic limit; results obtained by this method, however, 
are generally from 5,000 to 15,000 pounds higher than the true 
elastic limit where this property is not in excess of 125,000 
pounds per square inch. With material having a yield point in 
excess of 125,000 pounds per square inch the true elastic limit 
should be obtained by means of an extensometer. 

There is little use in giving the physical characteristics of a 
carbonized steel, inasmuch as any test must be deceptive because 
of the very high carbon exterior case, which cracks and fails 
long before the soft and tough interior does. This means that 
the rupture is fragmental and progressive and misleading. 

In addition to the usual physical characteristics the "hard- 
ness" tests have been considered, as obtained by means of the 
Brinell ball test and the Shore scleroscope. The Brinell test 
recommended by the committee is the use of the 10-millimeter 
ball and 3,000-kilogram load. It is pointed out, however, that the 
Brinell test must not be used on soft steels less than y 2 inch 
thick, or on areas small enough to permit the depression to flow 
toward the edges of the specimen. With hard steels, where the 
depth of the depression and the flow of metal are less, material 
as thin as Y^ inch may be so tested. The Brinell test may be 
fairly made on surfaces that are free from scale and smooth. 



S. A. E. SPECIFICATIONS 123 

The Shore test (scleroscope) must be used only on surfaces 
that have been carefully polished and freed from all tool marks, 
file marks or grinding scratches. The test specimen should also 
be of such mass or be held in such manner as to give the greatest 
possible freedom from deflection when struck by the hammer. 

CARBON STEELS 

SPECIFICATION NO. 1010 

.10 Carbon Steel 

This is usually known in the trade as soft, basic open-hearth 
steel. It is a material commonly used for seamless tubing, pressed 
steel frames, pressed steel brake-drums, sheet steel brake-bands 
and pressed steel parts of many varieties. It is soft and ductile, 
and will stand much deformation without cracking . 

This steel in a natural or annealed condition has little tenacity, 
and must not be used where much strength is required. This 
quality of material is considerably stronger after cold drawing 
or rolling; that is, its yield point is raised by such working. 
This is important in view of the fact that many wire and sheet 
metal parts above mentioned are used in the cold rolled or cold 
drawn form. 

It must not be forgotten that when this steel (so cold worked) 
is heated, as for bending, brazing, welding or the like, the yield 
point returns to that characteristic of the annealed material. 
This remark also applies to all materials that have an increased 
yield point produced by cold working. 

This material in a natural or annealed state does not machine 
freely. It will tear badly in turning, threading and broaching 
operations. Heat treatment produces but little benefit, and that 
not in strength but in toughness. It is possible to quench this 
grade of steel and put it in a condition to machine better than 
in the annealed state. 

The heat treatment which will produce a little stiffness is to 
quench at 1500° Fahr. in oil or water. No drawing is required. 



124 STEEL AND ITS TREATMENT 

Physical Characteristics 

Cold Rolled 
or 
Annealed Cold Drawn 

Yield point, lbs., per sq. in .... . 28,000 40,000 . 

to to 

36,000 60,000* 

Reduction of area 65-55% 55-45% 

Elongation in 2" 40-30% Unimportant 

This steel will case-harden, but is not as suitable for this pur- 
pose as Steel 1020, a note on which follows : 

SPECIFICATION NO. 1020 

.20 Carbon Steel 

This steel is known to the trade as .20 carbon, open-hearth 
steel, and often as machine steel. 

This quality is intended primarily for case-hardening. It 
forges well and machines well, but should not be considered as 
screw machine stock. It may therefore be used for a very large 
variety of forged, machined and case-hardened parts of an auto- 
mobile where strength is not paramount. 

Steel of this quality may also be drawn into tubes and rolled 
into cold-rolled forms, and, as a matter of fact, makes a better 
frame than Steel 1010, because of the slightly higher carbon and 
resulting strength. The increased carbon content has no detri- 
mental effect as far as usage is concerned, and it is only the most 
difficult of cold-forming operations that cause it to crack during 
the forming. For automobile parts it may be safely used inter- 
changeably with Steel 1010 as far as cold-pressed shapes are 
concerned. 

Heat treatment of this steel produces but little change as far 
as strength is concerned, but does cause a desirable refinement of 
grain after forging, and materially increases the toughness. The 
following treatment, which will often help the machining qual- 
ities, is all that is necessary : 

"These high yield points can be obtained only in comparatively 
light or small sections, either in the sheet or rod form ; say one-half 
inch round or one-quarter inch sheets or flats. 



S. A. E. SPECIFICATIONS 125 

Heat Treatment H 
After forging or machining: 

1. Heat to 15OO°-160O° Fahr. 

2. Quench. 

3. Reheat to 600°-1200° Fahr. and cool slowly. 
Case-hardening is the most important treatment for this 

quality of steel. The character of the operation must depend 
upon the importance of the part to be treated, and upon the 
shape and size. There is a certain group of parts in an automo- 
bile which are not called upon to carry much load or withstand 
any shock. The principal requirement is hardness. Such parts 
are fairly illustrated by screws and by rod-end pins. The simplest 
form of case-hardening will suffice, viz. : 

Heat Treatment A 
After forging or machining : 

1. Carbonize at a temperature between 1600° Fahr. and 

1750° Fahr. (1650°-1700° Fahr. desired). 

2. Cool slowly or quench. 

3. Reheat to 1450°-1500° Fahr. and quench. 

Another class of parts demands the best treatment (Heat Treat- 
ment B), such as gears, steering-wheel pivot-pins, cam-rollers, 
push-rods and many similar details of an automobile, which, the 
manufacturer learns by experience, must be not only hard on the 
exterior surface, but must possess strength as well. The desired 
treatment is one which first refines and strengthens the interior 
and uncarbonized metal. This is then followed by a treatment 
which refines the exterior carbonized or high-carbon metal. 

Heat Treatment B 

After forging or machining : 

1. Carbonize at a temperature between 1600° Fahr. and 

1750° Fahr. (1650°-1700° Fahr. desired). 

2. Cool slowly in the carbonizing mixture. 

3. Reheat to 1550°-1625° Fahr. 

4. Quench. 

5. Reheat to 1400°-1450° Fahr. 

6. Quench. 



126 STEEL AND ITS TREATMENT 

7. Draw in hot oil at a temperature which may vary from 
300° Fahr. to 450° Fahr., depending upon the degree 
of hardness desired. 

In the case of very important, parts, the last drawing operation 
should be continued from one to three hours to insure the full 
benefit of the operation. 

The objects of drawing are two-fold: First, and not least im- 
portant, is the relieving of all internal strains produced by quench- 
ing; second is the decrease in hardness, which is sometimes de- 
sirable. The hardness begins to decrease very materially from 
350° Fahr. up, and the operation must be controlled as dictated 
by experience with any given part. 

There are certain very important pieces that demand all of 
these operations, but the last drawing operation may be omitted 
with a large number. Experience teaches what degree of hard- 
ness and toughness combined is necessary for any given part. It 
is impossible to lay down a general rule covering all different 
uses. If the fundamental principle is well understood there 
should be no trouble in developing the treatment to a proper 
degree. 

Following the foregoing treatment, a fractured part should 
show a fine-grained exterior, without any appearance of shiny 
crystals. The smaller the crystals the better. The interior may 
show a silky, fibrous condition or a fine crystalline condition; but 
it must not show a coarse, shiny, crystalline condition. 

Physical Characteristics 
When cold rolled or cold drawn this steel will have a yield 
point of 40,000 to 75,000* pounds per square inch and a reduction 
of area from 35 to 30 per cent. 

SPECIFICATION NO. 1025 

.25 Carbon Steel 

This steel is used most widely for frames and for ordinary 

drop forgings where moderate ductility is desired but high 

strength is not essential. Heat treatment has a moderate effect 

* In sections not over one-half inch round or one-quarter inch sheett 
or flats. 



S. A. E. SPECIFICATIONS 127 

on the physical properties, but this effect is not nearly so marked 
as on Steel 1035. 

Heat treatment H or D may be used for this quality of steel. 

Heat treatment H is the simplest form of heat treatment ; the 
drawing operation (No. 3) must be varied to suit each individual 
case. If great toughness and little increased strength are desired, 
the higher drawing temperatures may be used, that is, in the 
neighborhood of 1100° Fahr. to i200° Fahr. If much strength is 
desired and little toughness, the lower temperatures are avail- 
able. Even the lowest of the temperatures given will produce a 
quality of steel, after oil quenching, that is very tough — suffi- 
ciently tough for many important parts. In fact, with some parts 
the drawing operation (No. 3) may be entirely omitted. 

Results better than obtainable with the above sequence of 
operations may be obtained by a double treatment, viz. : 

Heat Treatment D 
After forging or machining: 

1. Heat to 1500°-1600° Fahr. 

2. Quench. 

3. Reheat to 1450°-1500° F. 

4. Quench. 

5. Reheat to 600°-1200° Fahr. and cool slowly. 

This produces a refinement of grain not possible with one 
treatment, and is resorted to in parts where extremely good quali- 
ties are desired. 

This quality of steel is not intended for case-hardening, but by 
careful manipulation it may be so treated. This should be done 
in emergencies only, rather than as a regular practice, and, if at 
all, only with the double treatment followed by the drawing opera- 
tion; that is, the most painstaking form of case-hardening. 

SPECIFICATION NO. 1035 

.35 Carbon Steel 

This material is sometimes referred to in the trade as .35 carbon 
machine steel. 

It is primarily for use as a structural steel. It forges well, 
machines well, and responds to heat treatment in the matter of 



128 STEEL AND ITS TREATMENT 

strength as well as toughness ; that is to say, intelligent heat treat- 
ment will produce marked increase in the yield point. It may be 
used for all forgings such as axles, driving-shafts, steering pivots 
and other structural parts. It is the best all-round structural steel 
for such use as its strength warrants. 

Heat treatment for toughening and strength is of importance 
with this steel. The heat treatment must be modified in accord- 
ance with the experience of the individual user, to suit the size 
of the part treated and the combination of strength and toughness 
desired. The steel should be heat-treated in all cases where re- 
liability is important. 

Machining may precede the following heat treatment, depend- 
ing somewhat upon convenience and the character of the treat- 
ment. If the highest strength is demanded, a strong quenching 
medium must be employed ; for example, brine. In such case 
the yield point will be correspondingly high and the steel corre- 
spondingly hard and difficult to machine. On the other hand, if a 
moderately high yield point is all that is desired, an oil quench 
will suffice, and machining may follow without any difficulty 
whatever. 

Heat treatment H, D or E may be used on this quality of steel. 
When heat treatment E is applied, machining may follow opera- 
tion 2. 

Heat Treatment E 
After forging or machining : 

1. Heat to 1500°-1550° Fahr. 

2. Cool slowly. 

3. Reheat to 1450°-1500° Fahr. 

4. Quench. 

5. Reheat to 600°-12W>° Fahr. and cool slowly. 

SPECIFICATION NO. 1045 

.45 Carbon Steel 
This material is ordinarily known to the trade as .45 carbon 
machine steel. This quality represents a structural steel of greater 
strength than Steel 1035. Its uses are more limited, and are con- 
fined, in a general way, to such parts as demand a high degree of 



S. A. E. SPECIFICATIONS 129 

strength and a considerable degree of toughness. At the same 
time, with proper heat treatment the fatigue-resisting (endur- 
ance) qualities are very high — higher than with any of the fore- 
going specifications. 

This steel is commonly used for crankshafts, driving-shafts and 
propeller-shafts. It has also been used for transmission gears, 
but it is not quite hard enough without case-hardening, and is 
not tough enough with case-hardening, to make safe transmis- 
sion gears. It should not be used for case-hardened parts. Other 
specifications are decidedly better for this purpose. 

In a properly annealed condition it machines well — not well 
enough for screw machine work, but certainly well enough for 
all-round machine-shop practice. Heat treatment E provides the 
annealing operation when needed, machining to follow opera- 
tion 2 ; this treatment is especially adapted to crankshafts and 
similar parts. Heat treatment H is also commonly used for this 
quality of steel. 

SPECIFICATION NO. 1095 
.95 Carbon Steel 
This is a grade of steel used generally for springs. Properly 
heat-treated, extremely good results are possible. 

The hardening and drawing of springs, that is, the heat treat- 
ment of them, is, as a rule, in the hands of the springmaker, 
but in case it is desired to treat, as for small springs, the follow- 
ing is recommended : 

Heat Treatment F 

After shaping or coiling: 

1. Heat to 1425°-1475° Fahr. 

2. Quench in oil. 

3. Reheat to 400° -900° Fahr., in accordance with degree of 

temper desired, and cool slowly. 
It must be understood that the higher the drawing temperature 
(Operation 3), the lower will be the yield point of the material. 
On the other hand, if the material be drawn at too low a tem- 
perature it will be brittle. A few practical trials will locate the 
best temper for any given shape or size. 
10 



130 STEEL AND ITS TREATMENT 

The physical characteristics of heat-treated spring steel are best 
determined by transverse test. This is because steel as hard as 
tempered spring steel is very difficult to hold firmly in the jaws 
of a tensile testing machine. There is more or less slip, and side 
strains are bound to occur, all of which tends to produce mis- 
leading results. 

The physical characteristics in the annealed condition may be 
omitted, inasmuch as this grade of steel is not ordinarily used 
for structural parts' in such condition. 

Careful examination of the fracture of the treated material is 
desirable. After tempering, no suitable spring steel should be 
coarsely crystalline. It should be finely crystalline, and in some 
cases will show a partly fibrous fracture. 

Physical Characteristics 

(Transverse Test) 

Heat Treatment F. 

Elastic limit (initial set), lbs. per sq. in 90,000 

to 
180,000 

Reduction of area Not determined 

in transverse test 
Elongation do 

SCREW STOCK 

SPECIFICATION NO. 1114 

This steel may be made by any process. It is intended for use 
where high screw machine production is the important factor, 
strength and toughness being secondary considerations. Its com- 
position and texture are of such nature as to permit the rapid 
removal of metal and a resulting smoothness of finish. 

STEEL CASTINGS 

SPECIFICATION NO. 1235 

In the following remarks, genuine steel castings, and not 
malleable iron or complex mixtures often found in the market 
masquerading under the name of steel, are referred to. 



S. A. E. SPECIFICATIONS 131 

All steel castings should be annealed, and some shapes may be 
heat-treated to great advantage. Like other castings, steel cast- 
ings are subject to blow-holes. Consequently they should not be 
used in the vital parts of an automobile. It is impossible to 
inspect against blow-holes, and steel castings for axles, crank- 
shafts and steering spindles are used only at great risk. Freedom 
from blow-holes and proper physical condition are of more im- 
portance than the absolute analysis. 

On account of the great influence of varying types of foundry 
practice upon the properties of castings, it has not been found 
feasible to give a closer specification for chemical composition 
than that quoted under No. 1235. If it is desired to buy steel 
castings under precise specifications, the following, based upon 
the "Specifications for Steel Castings, Class B, Serial Designa- 
tion A 27-14," of the American Society for Testing Materials, 
can be used : 

I. Manufacture 

1. The steel may be made by any process approved by the 
purchaser. Three grades are recognized : hard, medium and 
soft. 

2. All castings shall be allowed to become cold; they shall then 
be reheated uniformly to the proper temperature to refine the 
grain, and allowed to cool uniformly and slowly. 

77. Chemical Properties and Tests 

3. No casting, on check analysis, shall show over .05 per cent, 
phosphorus or sulphur. The carbon content shall be suitable 
for the physical tests and service required. 

4. Drillings for analysis shall be so taken as to represent the 
average composition of the casting. 

III. Physical Properties and Tests 

5. The finished castings shall conform to the following mini- 
mum requirements as to tensile properties : 

Hard Medium Soft 

Tensile strength, lb. per sq. in.... 80,000 70,000 60,000 

Yield point, lb. per sq. in 36,000 31,500 27,000 

Reduction of areas, per cent 20 25 30 

Elongation in 2 in., per cent 15 18 22 



132 STEEL AND ITS TREATMENT 

6. The test specimen for soft castings shall bend cold through 
120 degrees, and for medium castings through 90 degrees, around 
a 1-inch pin, without cracking on the outside. Hard castings shall 

not be subject to bent-test requirements. 

7. In the case of small or unimportant castings, a test to de- 
struction on three castings from a lot may be substituted for the 
tension and bend tests. This test shall show the material to be 
ductile, free from injurious defects, and suitable for the purpose 
intended. A lot shall consist of all castings from one melt, in 
the same annealing charge. In case test bars are cast separate, 
they shall be annealed with the lot they represent, the method of 
casting such test bars, or of casting test bars attached to cast- 
ings, to be agreed upon by purchaser and manufacturer. 

8. Tension test specimens shall be machined to the standard 
S. A. E. form; bend test specimens shall be machined to 1 by J^ 
inch in section, with corners rounded to a radius not over 1/16 
inch. 

9. One tension and one bend test shall be made from each 
annealing charge. If more than one melt is represented in an 
annealing charge, one tension and one bend test shall be made 
from each melt. 

10. If any test specimen shows defective machining or de- 
velops flaws, it may be discarded, in which case another speci- 
men may be selected by the manufacturer and the purchaser. 

11. A retest shall be allowed if the percentage of elongation 
is less than that specified or if any part of the fracture is more 

than % inch from the center of the gauge length as indicated 
by scribe scratches marked on the specimen before testing. 

IV. Workmanship and Finish. 

12. The finished castings shall conform substantially to the 
sizes and shapes of the patterns, shall be made in a workmanlike 
manner, and be free from injurious defects. 

13. Minor defects which do not impair the strength of the 
castings may, with the approval of the purchaser, be welded by 
an approved process. The defects shall first be cleaned out to 
solid metal, and, after welding, the castings shall be annealed. 



S. A. E. SPECIFICATIONS 133 

14. Castings offered for inspection shall not be painted or 
covered with any substance that will hide defects, nor rusted to 
such an extent as to hide defects. 

ALLOY STEELS 

In connection with the purchase and use of alloy steels it should 
be borne in mind that such steels should be used in the treated 
condition only, that is, not in an annealed or natural condition. 
In the latter condition there is a slight benefit, perhaps, as com- 
pared with plain carbon steels, but as a rule nothing com- 
mensurate with the increased cost. In the heat-treated condition, 
however, there is a very marked improvement in physical char- 
acteristics. 

NICKEL STEELS 

SPECIFICATION NO. 2315 
.15 Carbon, 2,y 2 % Nickei, StEEi, 

This quality of steel is embraced in these specifications to fur- 
nish a nickel steel that is suitable for carbonizing purposes. Steel 
of this character, properly carbonized and heat-treated, will pro- 
duce a part with an exceedingly tough and strong core, coupled 
with the desired high carbon exterior. 

This steel is also available for structural purposes, but is not 
one to be selected for such purpose when ordering materials. 
Much better results will be obtained with one of the other nickel 
steels of higher carbon. 

It is intended for case-hardened gears, for both the bevel driv- 
ing and transmission systems, and for such other case-hardened 
parts as demand a very tough, strong steel with a hardened 
exterior. 

The case-hardening sequence may be varied considerably, as 
with Steel 1020, those parts of relatively small importance re- 
quiring a simpler form of treatment. As a rule, however, those 
parts which require the use of nickel steel require the best type 
of case-hardening, viz. : 



134 STEEL AND ITS TREATMENT 

Heat Treatment G 
After forging or machining : 

1. Carbonize at a temperature between 1600° Fahr. and 

1750° Fahr. (165a°-l700° Fahr. desired). 

2. Cool slowly in the carbonizing material. 

3. Reheat to 150O°-1550° Fahr. 

4. Quench. 

5. Reheat to 130O°-140O° Fahr. 

6. Quench. 

7. Reheat to 250°-500° Fahr. (in accordance with the neces- 

sities of the case) and cool slowly. 

The second quench (Operation 6) must be conducted at the 
lowest possible temperature at which the material will harden. It 
will be found that sometimes this is lower than 1300° Fahr. 

In connection with certain uses it will be found possible to 
omit the final drawing (Operation 7) entirely, but for parts of 
the highest importance this operation should be followed as a 
safeguard. Parts of intricate shape, with sudden changes of 
thickness, sharp corners and the like, particularly sliding gears, 
should always be drawn, in order to relieve the internal strain. 

Much is to be learned from the character of the fracture. The 
center should be fibrous in appearance, and the exterior, high- 
carbon metal closely crystalline, or even silky. 

When used for structural purposes, the physical characteristics 
will range about as follows : 

Physical Characteristics 

Heat Treat- 
Annealed ment H or K 

Yield point, lbs. per sq. in 35,000 40,000 

to to 

45,000 80,000 

Reduction of area 65-45% 65-40% 

Elongation in 2" 35-25% 35-15% 

SPECIFICATION NO. 2320 
.20 Carbon, 3 j / 2 % Nickel Steel 
This quality may be used interchangeably with Steel 2315. Al- 
though intended primarily for case-hardening, it may be properly 



S. A. E. SPECIFICATIONS 135 

used for structural parts, with suitable heat treatment, and will 
give elastic limits somewhat higher than material provided by 
the preceding specification. 

For case-hardening, Heat Treatment G should be followed, and 
for structural purposes the treatment should be in accordance 
with Heat Treatment H or K, the quenching temperatures, as 
with other steels, being modified to meet individual cases. 

Heat Treatment K 
After forging or machining : 

Heat to 1500°-1550° Fahr. 

Quench. 

Reheat to 1300°-1400° Fahr. 

Quench. 

Reheat to 600°-1200° Fahr. and cool slowly. 

Physical Characteristics 

Heat Treat - 
Annealed ment H or K 

Yield point, lbs. per sq. in 40,000 50,000 

to to 

50,000 125,000' 

Reduction of area 65-40% 65-40% 

Elongation in 2" 30-20% 25-10% 

SPECIFICATION NO. 2330 
.30 Carbon, 3^% Nickel Steel 

This quality of steel is primarily for heat-treated structural 
parts where strength and toughness are sought, such parts as 
axles, front-wheel spindles, crankshafts, driving-shafts and trans- 
mission shafts. Wide variations of yield point or elastic limit 
are possible by the use of different quenching mediums — oil, water 
or brine — and variation in drawing temperatures, from 500° Fahr. 
up to 1200° Fahr. (Heat Treatment H). 

A higher refinement of this treatment is Heat Treatment K. 

Physical Characteristics 

The physical characteristics of this steel may be considered as 
practically those obtained with Steel 2320, slight modifications 



136 STEEL AND ITS TREATMENT 

in the treatment much more than offsetting the slight difference 
in the carbon content. 

Heat Treat- 
Annealed ment H or K 

Yield point or elastic limit, lbs r per 

sq. in 40,000 60,000 

to to 

50,000 130,000 

Reduction of area 60-40% 60-30% 

Elongation in 2" 30-20% 25-10% 

SPECIFICATION NO. 2335 

.35 Carbon, 3^% Nickel Steel 
This quality of steel is subject to precisely the same remarks 
as Steel 2330. It will respond a little more sharply to heat treat- 
ment, and can be forced to higher elastic limits. The difference 
will be small except in extreme cases. 

Physical Characteristics 

Heat Treat- 
Annealed ment H or K 

Yield point or elastic limit, lbs. per 

sq. in 45,000 65,000 

to to 

55,000 160,000 

Reduction of area 55-35% 55-25% 

Elongation in 2" 25-15% 25-10% 

SPECIFICATION NO. 2340 
.40 Carbon, 3^4% Nickel Steel 

The above nickel steel is a quality not in wide use but avail- 
able for certain purposes. The carbon content being higher than 
generally used, greater hardness is obtainable by quenching; and, 
as increased brittleness accompanies the greater hardness, the 
treatments given must be modified to meet such condition. For 
example, the final quench may be at a considerably lower tempera- 
ture, and the final drawing temperature, or partial annealing, must 
be carefully chosen, in order to produce the desired toughness 
and other physical characteristics. 



S. A. E. SPECIFICATIONS 137 

Physical Characteristics 

Heat Treat- 
Annealed ment HorK 

Yield point or elastic limit, lbs. per 

sq. in 55,000 70,000 

to to 

65,000 200,000 

Reduction of area 50-30% 55-15% 

Elongation in 2" 25-15% 20- 5% 

NICKEL CHROMIUM STEELS 

In general it may be said in the case of the Nickel Chromium 
Steels that the heat treatments and the properties induced thereby 
are much the same as in the case of plain nickel steels, except 
that the effects of the heat treatments are somewhat augmented 
by the presence of the chromium, and, further, that these effects 
increase with increasing amounts of nickel and chromium. 

SPECIFICATION NO. 3120 

This quality of steel is intended primarily for case-hardening 
(Heat Treatment G). It may also be used for structural parts 
with suitable heat treatment (Heat Treatment H or D). It 
should not be used in the natural or untreated condition. 

Physical Characteristics 

Heat Treat- 
Annealed ment H or D 

Yield point or elastic limit, lbs. per 

sq. in 30,000 40,000 

to to 

40,000 100,000 

Reduction of area 55-40% 65-40% 

Elongation in 2" 35-25% 25-15% 

SPECIFICATIONS NOS. 3125, 3130, 3135, 3140 

These qualities of steel are intended primarily for structural 
purposes in a heat-treated condition (Heat Treatment H, D or 
E). Steel 3125 may be used for case-hardening, as also may 
Steel 3130 if necessary. 



138 



STEEL AND ITS TREATMENT 
Physical Characteristics 



Steels 3125, 3130: 

Annealed 
Yield point or elastic limit, lbs. per 

sq. in 40,000 

to 
55,000 

Reduction of area 50-35% 

Elongation in 2" 



30-20% 



Steels 3135, 3140 



Annealed 
Yield point or elastic limit, lbs. per 

sq. in 45,000 

to 
60,000 

Reduction of area 45-30% 

Elongation in 2" 25-15% 



Heat Treat- 
ment H, D 
or E 



50,000 

to 
125,000 
55-25% 
25-10% 



Heat Treat- 
ment H, D 
or E 



55,000 

to 
150,000 
50-25% 
20 -5% 



SPECIFICATION NO. 3220 

This steel is intended for case-hardened parts of nickel chro- 
mium steel. Case-hardened parts demanding this grade of steel 
also demand the most careful heat treatment (Heat Treatment 
G). It may also be used for structural purposes with Heat Treat- 
ment H or D. 



Physical Characteristics 

Annealed 
Yield point or elastic limit, lbs. per 

sq. in 35,000 

to 
45,000 

Reduction of area 60-45% 

Elongation in 2" 25-20'% 



Heat Treat- 
ment H or D 



45,000 

to 
120,000 
65-30% 
20- '5% 



SI A. E. SPECIFICATIONS 139 

SPECIFICATION NO. 3230 

This steel is intended for the most important structural parts, 
and should be used only in a heat-treated condition (Heat Treat- 
ment H or D). 

Physical Characteristics 

Heat Treat- 
Annealed merit H or D 
Yield point or elastic limit, lbs. per 

sq. in 40,000 60,000 

to to 

50,000 175,000 

Reduction of area 55-40% 60-30% 

Elongation in 2" 25-15% 20- 5% 

SPECIFICATION NO. 3240 

This quality of steel is suitable for structural parts where 
unusual strength is demanded. Higher elastic limit is possible 
under a given treatment than with material like Steel 3230. The 
toughness will not be quite as great, but this does not bar the 
material from uses where toughness is not the controlling factor 
and where strength is. 

Heat Treatment H or D is recommended. 

Physical Characteristics 

Heat Treat - 
Annealed ment IT or D 

Yield point or elastic limit, lbs. per 

sq. in 45,000 65,000 

to to 

60,000 200,000 

Reduction of area 50-40% 50-20% 

Elongation in 2" 25-15% 15- 2% 

SPECIFICATION NO. 3250 

This steel is intended for gears where extreme strength and 
hardness are necessary. 

To heat-treat for gears, either Heat Treatment M or Q should 
be followed, the latter giving the better results. 



140 STEEL ' AND ITS TREATMENT 

Heat Treatment M 
After forging or machining: 

1. Heat to 1450°-1500° Fahr. 

2. Quench. 

3. Reheat to 500°-12o0° Fahr. and cool slowly. 
A higher refinement of this same treatment is : 

Heat Treatment Q 
After forging: 

1. Heat to 1475°-1525° Fahr. (Hold at this temperature 

one-half hour to insure thorough heating.) 

2. Cool slowly. 

3. Reheat to 1375°-1425° Fahr. 

4. Quench. 

5. Reheat to 25O°-550° Fahr. and cool slowly. 

Physical Characteristics 

Heat Treat- 
Annealed ment M or Q 
Yield point or elastic limit, lbs. per 

sq. in 50,000 150,000 

to to 

60,000 250,000 

Reduction of area 50-40% 25-15% 

Elongation in 2" 25-15% 15- 2% 

SPECIFICATION X3315 

This steel is intended primarily for case-hardening. It is higher 
in nickel and chromium than the preceding nickel chromium 
steels. Heat Treatment G should be followed. 

It is sometimes used for structural parts, when Heat Treat- 
ment M is applicable. 

Physical Characteristics 

Heat Treat- 
Annealed ment M 
Yield point or elastic limit, lbs. per 

sq. in 35,000 40,000 

to to 

45,000 100,000 

Reduction of area 60-45% 65-30% 

Elongation in 2" 25-20% 20- 5% 



S. A. E. SPECIFICATIONS 141 

SPECIFICATION X3335 

This steel is intended for structural parts of the most important 
character, such as crankshafts, axles, spindles, drive-shafts and 
transmission shaft. Heat Treatment P or R is recommended. 

This steel is not intended for case-hardening. 

Heat Treatment P 
After forging or machining: 

1. Heat to 1450°-1500° Fahr. 

2. Quench. 

3. Reheat to 1375°-1450° Fahr. 

4. Quench. 

5. Reheat to 50O°-1250° Fahr. and cool slowly. 

Heat Treatment R 
After forging: 

1. Heat to 1500°-1550° Fahr. 

2. Quench in oil. 

3. Reheat to 1200°-1300°. (Hold at this temperature three 

hours.) 

4. Cool slowly. 

5. Machine. 

6. Reheat to 1350°-1450° Fahr. 

7. Quench in oil. 

8. Reheat to 250° -500° Fahr. and cool slowly. 

Physical Characteristics 

Heat Treat - 
Annealed ment P or R 

Yield point or elastic limit, lbs. per 

sq. in 45,000 60,000 

to to 

55,000 175,000 

Reduction of area 55-40% 60-30% 

Elongation in 2" 25-15% 20- 5% 

SPECIFICATION X3350 

This steel is an alternative quality for gears. The remarks 
made on Steel 3250 apply to this case. The physical character- 
istics are similar to those of Steel 3250. Heat Treatment R 
should be used, although P is applicable. 



142 STEEL AND ITS TREATMENT 

SPECIFICATION NO. 3320 
The remarks made in connection with Steel 3220 apply to this 
steel also. There is no appreciable difference in the physical 
characteristics. Carbonizing should follow the practice indicated 
under Heat Treatment L. 

Heat Treatment L 
After forging or machining: 

1. Carbonize at a temperature between 1600° Fahr. and 1750° 

Fahr. (1650°-1700° Fahr. desired). 

2. Cool slowly in the carbonizing mixture. 

3. Reheat to 1400°-1500° Fahr. 

4. Quench. 

5. Reheat to 1300°-1400° Fahr. 

6. Quench. 

7. Reheat to 250°-500° Fahr. and cool slowly. 

SPECIFICATION NO. 3330 

This steel, like No. 3230, is intended for very important struc- 
tural parts. The high nickel and chromium contents make it 
exceedingly tough and strong when treated, according to Heat 
Treatment P or R. 

SPECIFICATION NO. 3340 
This steel is suitable for gears to be hardened without car- 
bonizing. The remarks made in connection with Steels 3240 and 
3250 apply. Heat Treatment P or R should be used. 

CHROMIUM STEELS 

SPECIFICATION NO. 5120 

This steel is similar in properties to 2320 and 3120 in that it is 
a case-hardening grade of much better quality than carbon steel. 
Heat Treatment B should be used. 

SPECIFICATION NO. 5140 

This grade of steel is very similar in properties to Steel 3140. 
When treated according to H or D it becomes useful for high- 



S. A. E. SPECIFICATIONS 143 

duty shafting, etc. The drawing temperature should be moder- 
ately high in order to maintain a safe degree of toughness. 

SPECIFICATIONS NOS. 5195, 51120, 5295, 52120 
These four grades of steel are used almost exclusively for ball 
bearing cups and cones where their extreme hardness is indis- 
pensable. The treatment of these steels is in the hands of spe- 
cialists, but in a general way Treatment P and R illustrate the 
procedures followed. 

CHROMIUM VANADIUM STEELS 

SPECIFICATION NO. 6120 
.20 Carbon, Chromium Vanadium Steel 

This quality is also primarily for case-hardening. It is used for 
the most important case-hardened parts; that is, case-hardened 
shafts, gears and the like. 

This steel may also be used in a heat-treated condition for 
structural purposes, but for such work some of the specifications 
following are to be preferred, particularly where higher strength 
is desired. 

The case-hardening treatment recommended is that covered by 
Heat Treatment S. 

Heat Treatment S 
After forging or machining: 

1. Carbonize at a temperature between 1600° Fahr. and 1750° 

Fahr. (1650°-1700° Fahr. desired). 

2. Cool slowly in the carbonizing mixture. 

3. Reheat to 1650°-1750° Fahr. 

4. Quench. 

5. Reheat to 1475°-1550° Fahr. 

6. Quench. 

7. Reheat to 250°-550° Fahr. and cool slowly. 

For structural purposes the following heat treatment is recom- 
mended : 

Heat Treatment T 

After forging or machining: 
1. Heat to 1650°-1750° Fahr. 



144 STEEL AND ITS TREATMENT 

2. Quench. 

3. Reheat to 500° -1300° Fahr. and cool slowly. 

Physical Characteristics 

Heat Treat- 
Annealed ment T 
Yield point or elastic limit, lbs. per 

sq. in 40,000 55,000 

to to 

50,000 100,000 

Reduction of area 65-50% 65-45% 

Elongation in 2" 30-20% 25-10% 

SPECIFICATION NO. 6125 
.25 Carbon, Chromium Vanadium Steel 

The difference between this and the preceding specification is 
very slight, and they may be used interchangeably for structural 
purposes. This steel may be case-hardened, but is not first choice 
for this purpose. 

The physical characteristics may be considered as practically 
the same as given for Steel 6120. 

Physical Characteristics 

Heat Treat- 
Annealed inent T 
Yield point or elastic limit, lbs. per 

sq. in 40,000 55,000 

to to 

50,000 100,000 

Reduction of area 65-50% 65-45% 

Elongation in 2" 32-20% 25-10% 

SPECIFICATION NO. 6130 
.30 Carbon, Chromium Vanadium Steel 

This quality of steel is intermediate in the carbon range, and 
may be used interchangeably with Steel 6125 for structural pur- 
poses. It should not be used for case-hardening. When sub- 
jected to Heat Treatment T it possesses a high degree of com- 
bined strength and toughness. 



S. A. E. SPECIFICATIONS 145 

Physical Characteristics tt l m 

Heat Treat- 
Annealed ment T 
Yield point or elastic limit, lbs. per 

sq. in 45,000 60,000 

to to 

55,000 150,000 

Reduction of area 60-50% 55-25% 

Elongation in 2" 25-20% 15- 5% 

SPECIFICATION NO. 6135 
.35 Carbon, Chromium Vanadium Steel 
This specification provides a first-rate quality of steel for struc- 
tural parts that are to be heat-treated. The fatigue-resisting (en- 
durance) qualities of this material are excellent. 

Physical Characteristics tt m 

Heat Treat- 
Annealed ment T 
Yield point or elastic limit, lbs. per 

sq. in 45,000 60,000 

to to 

55,000 150,000 

Reduction of area 60-50% 55-25% 

Elongation in 2" 25-20% 15- 5% 

SPECIFICATION NO. 6140 
.40 Carbon, Chromium Vanadium Steel 
This is a very good quality of steel to be selected where a high 
degree of strength is desired, coupled with a good measure of 
toughness. Its fatigue-resisting qualities are very high, and it is 
a first-class material for high-duty shafts. 
Heat Treatment T is recommended. 

Physical Characteristics tt m 

Heat Treat- 
Annealed ment T 
Yield point or elastic limit, lbs. per 

sq. in 50,000 65,000 

to to 

60,000 175,000 

Reduction of area 55-45% 50-15% 

Elongation in 2" 25-15% 15- 2% 

11 



146 STEEL AND ITS TREATMENT 

SPECIFICATION NO. 6145 

.45 Carbon, Chromium Vanadium Steel 

This quality of steel contains sufficient carbon in combination 

with chromium and vanadium to harden to a considerable degree 

when quenched at a proper temperature, and may be used for 

gears and springs. 

For structural parts where exceedingly high strength is desir- 
able, Heat Treatment T should be followed. 

For gears this steel should be annealed after forging, and be- 
fore machining, the anneal to consist of Operations 1 and 2 of the 
following : 

Heat Treatment U 
After forging : 

1. Heat to 1525°-1600° Fahr. (Hold at this temperature 

one-half hour to insure thorough heating.) 

2. Cool slowly. 

3. Reheat to 1650°-1700° Fahr. 

4. Quench. 

5. Reheat to 350°-550° and cool slowly . 

This last drawing operation may be modified to obtain any 
desired hardness. 

Physical Characteristics 

Heat Treat- 
Annealed ment U 

Yield point or elastic limit, lbs. per 

sq. in 55,000 150,000 

to to 

65,00.0 200,000 

Reduction of area 55-40% 25-10% 

Elongation in 2" 25-15% 10- 2% 

SPECIFICATION NO. 6150 

.50 Carbon, Chromium Vanadium Steel 

Substantially the same remarks as made in regard to Steel 6145 
apply to this quality. In this grade, however, we also find a mate- 
rial that is suitable for springs. With a proper sequence of heat- 
ing, quenching and drawing, very high elastic limits are obtained. 

For spring material Heat Treatment U is recommended, except 



S. A. E. SPECIFICATIONS 147 

that the last drawing (Operation 5) will be carried farther — prob- 
ably from 700°-1100° Fahr. This final drawing temperature will 
have to vary with the section of material being handled, whether 
light spiral springs or heavy flat springs. 

Physical Characteristics 

Heat Treat- 
Annealed nient U 
Yield point or elastic limit, lbs. per 

sq. in ' 60,000 150,000 

to to 

70,000 • 225,000 

Reduction of area 50-35% 35-15% 

Elongation in 2" 20-15% 10- 2% 

SILICO-MANGANESE STEELS 

SPECIFICATIONS NOS. 9250 AND 9260 
These steels have been standardized by using principally as 
spring steels. No. 9260 is also used to some extent for gears. 
Neither steel is suitable for use without heat treatment. 

Both of these specifications are provided in order to meet the 
requirements of two groups of users : those who believe in rela- 
tively low carbon and high silicon, and those who desire higher 
carbon and lower silicon. When properly treated their physical 
properties will not differ appreciably, though Steel 9250 will prob- 
ably be slightly the tougher of the two. Heat Treatment V is 
suitable for both gears and springs. 

Heat Treatment V 
After forging or machining : 

1. Heat to 1650°-1750° Fahr. 

2. Quench. 

3. Reheat to 40O°-1200° Fahr. and cool slowly. 

Steel 9260 will become harder when quenched in the same 
medium as Steel 9250. The latter, however, is more often 
quenched in water, while Steel 9260 is generally quenched in oil — 
a circumstance which largely counteracts the influence of the 
composition. Furthermore, variation in the temperature of draw- 
ing will suffice to balance the properties closely. 



148 STEEL AND ITS TREATMENT 

The exact temperature for quenching and drawing and the 

proper medium should be determined for each case. In general, 

gears are drawn between 450° and 550° Fahr., and springs be- 
tween 800° and 1000° Fahr. 

Physical Characteristics 

Heat Treat- 
Annealed ment V 
Yield point or elastic limit, lbs. per 

sq. in 55,000 60,000 

to to 

65,000 180,000 

Reduction of area 45-30% 40-10% 

Elongation in 2" 25-20% 20- 5% 



PHYSICAL PROPERTIES OF HEAT TREATED 
CARBON STEELS 

In interpreting the physical property curves and tabulations given 
in the following data, these considerations should be borne in mind : 

1. The figures given have been made as valuable as 
possible to the engineer by indicating what can be ex- 
pected as the average product of a given composition 
when treated in the specified manner, in average sec- 
tions prevailing in motor car work. 

2. At the same time the data have been so chosen as 
to protect makers of treated stock and parts from un- 
reasonable demands. This has been done by taking 
figures low enough to be obtained with reasonable cer- 
tainty when open market stock of medium to high 
grade is treated in commercially efficient equipment, 
controlled by commercially accurate instruments. 

For the sake of simplicity only' average minimum figures for 
tensile strength, elastic limit, reduction of area and elongation have 
been adopted ; these figures are based upon the following assump- 
tions, heat treatment being kept constant : 

1. The lowest tensile strength and elastic limit are 
produced with steels at the bottom of a given range in 
carbon. 

2. The lowest reduction in area and elongation are 
produced with steels at the top of a given range in 
carbon. 

Thus, for 1035 steel, the tensile strengths and elastic limits given 
are the average minimum as of a steel containing .30 per cent, car- 
bon ; the reductions of area and elongation are the average minimum 
as of a steel containing .40 per cent, carbon. 

True elastic limits are given because they are consistently lower 
than the corresponding yield points. 

The figures for hardness are conventional averages for the whole 
range of compositions within any given specification. In general, 
the Brinell hardness figure is subject to fluctuations of plus or 
minus ten to fifteen points, the Shore (scleroscope) hardness of 
plus or minus five points. 

Specimens for test must comply with all the requirements given 
under remarks concerning general physical property data. In addi- 
tion, tensile test pieces are to be taken concentrically from bars 
which are treated in diameters up to and including one inch round 
or square; from larger sections- the axis of the test piece should 
be made parallel to the axis of the bar at any point as nearly as 
possible 50 per cent, from the center to the exterior. 



150 



STEEL AND ITS TREATMENT 



PHYSICAL CHARACTERISTICS OF HEAT TREATED' S. A. E. STEEL NO. 1020 



z 


400 


500 


600 


DEGR 
700 


EES- FAHRENHEIT 
800 900 1000 


1100 


1200 1300 


80 o 160 

CO 


















































































275 £150 


















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_r^_ 




^0.70^140 

& 3265^ 130 
2-9 O 
= t360col20 

= 9 
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£^40^ 80 


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£10 £ 20 














































































B. 


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800 
750 
700 
650 <g 

600 1 
550 1 



500 



U 



400 x 



350 < 

CD 



250 rf 

200 1 
oa 

150 
100 



205 260 315 



370 425 480 540 
DEGREES- CENTIGRADE 



595 650 705 



50 




Heat Treatment 

The accompanying data apply to y 2 in. to iy 2 in. round specimens 
which were heated from 15 to 30 min at 1560° to 1580° Fahr. ; 
quenched in oil ; reheated for 30 min. at temperatures indicated by the 
abscissae of the curves; and finally cooled in air. (Heat Treatment H.) 



TABULATION OF VALUES PLOTTED IN 


CURVE 




Reheating 


Tensile 


Elastic 


Reduc- 


Elonga- 




Sclero- 


Tempera- 


Strength, 


Limit, 


tion of 


tion 


Brinell 


scope 


ture, 


Lb. per 


Lb. per 


Area, 


in 2 In., 


Hard- 


Hard- 


Deg. F. 


Sq. In. 


Sq. In. 
50,000 


per Cent. 
60.0 


per Cent. 


ness 


ness 


400 


80,000 


20.0 


180 


34 


500 


79,000 


49,000 


60.5 


20.5 


175 


34 


600 


78,000 


48,000 


61.0 


21.0 


170 


34 


700 


77,000 


46,500 


62.0 


22.5 


160 


33 


800 


76,000 


44,500 


63.5 


24.5 


150 


33 


900 


75,000 


42,500 


65.0 


26.5 


140 


32 


1000 


74,000 


40,500 


66.5 


28.5 


130 


32 


1100 


73,000 


38,500 


68.0 


30.0 


120 


31 


1200 


72,000 


37,000 


69.0 


31.5 


110 


31 


1300 


71,000 


36,000 


69.5 


32.0 


105 


30 


1400 


70,000 


35,000 


70.0 


32.5 


100 


30 



Values are average minimum, except those for hardness, which are average. 



S. A. E. SPECIFICATIONS 



151 



PHYSICAL CHARACTERISTICS OF HEAT TREATED- S. A. E. STEEL N0.1Q25. 



400 500 600 



DEGREES- FAHRENHEIT 
700 800 900 1000 



1100 1200 1300 



80 o,160 

CO 

w75 £ 150 
% £ 
^u.70 00 140 

tto g 

£2=65^130 
22 o 
= £60</>120 




205 260 315 



370 425 480 540 
DEGREES- CENTIGRADE 



595 650 705 



Heat Treatment 

The accompanying data apply to x / 2 in. to 1% in. round specimens 
which were heated from 15 to 30 min. at 1540° to 1580° Fahr. ; quenched 
in oil; reheated for 30 min. at temperatures indicated by the abscissae 
of the curves; and finally cooled in air. (Heat Treatment H.) 



TABULATION OF VALUES PLOTTED IN 


CURVE 




Reheating 


Tensile 


Elastic 


Reduc- 


Elonga- 




Sclero- 


Tempera- 


Strength, 


Limit, 


tion of 


tion 


Brinell 


scope 


ture, 


Lb. per 


Lb. per 


Area, 


in 2 In., 


Hard- 


Hard- 


Deg. F. 


Sq. In. 


Sq. In. 
60,000 


per Cent. 
55.0 


per Cent. 
17.0 


ness 
~~ 215 - 


ness 


400 


90,000 


37 


500 


89,000 


59,000 


55.5 


17.5 


210 


37 


600 


88,000 


57,000 


56.0 


18.5 


200 


36 


700 


86,500 


55,000 


57.5 


20.0 


185 


36 


800 


84,500 


52,500 


59.0 


21.5 


175 


35 


900 


82,500 


50,000 


61.0 


23.5 


160 


34 


1000 


80,500 


47,500 


63.0 


25.5 


145 


33 


1100 


78,500 


45,000 


64.5 


27.0 


135 


32 


1200 


77,000 


43,000 


66.0 


28.5 


125 


31 


1300 


76,000 


41,000 


67.0 


29.5 


115 


30 


1400 


75,000 


40,000 


67.5 


30.0 


110 


30 



Values are average minimum, except those for hardness, which are average. 



152 



STEEL AND ITS TREATMENT 



PHYSICAL- CHARACTERISTICS OF HEAT TREATED- S. A. E. STEEL NO. 1035 



z 

80 o- 160 
in 

*75 £150 

^u.70^140 

£ 265^ 130 
59 o 
= £60</>120 

= Q 
^2551110 

o os50 o 100 

x£45 



400 500 600 



DEGREES- FAHRENHEIT 
700 800 900 1000 



1100 1200 1300 



£^40t 
eg S 

35 



o 



o 
o 

CO 

o — 
3o30k 
^§25 3 

U.320X 
ocuj 5 

X z Hi 
couj a: 

£ *2 



90 

80 

70 

60 

50 

40 

30 

20 

10 





205 260 315 



370 425 480 540 
DEGREES- CENTIGRADE 



595 650 705 



Heat Treatment 

The accompanying data apply to y 2 in. to 1% in. round specimens 
which were heated from 15 to 30 min. at 1510° to 1530° Fahr. ; 
quenched in oil ; reheated for 30 min. at temperatures indicated by the 
abscissae of the curves; and finally cooled in air. (Heat Treat- 
ment H.) 

TABULATION OF VALUES PLOTTED IN CURVE 



Reheating 


Tensile 


Elastic 


Reduc- 


Elonga- 




Sclero - 


Tempera- 


Strength, 


Limit, 


tion of 


tion 


Brinell 


scope 


ture, 


Lb. per 


Lb. per 


Area, 


in 2 In., 


Hard- 


Hard- 


Deg. F. 


Sq. In. 


Sq. In. 


per Cent. 


per Cent. 


ness 


ness 


400 


105,000 


75,000 


42.5 


15.0 


260 


42 


500 


104,000 


74,000 


43.5 


15.5 


255 


42 


600 


102,500 


72,000 


45.0 


16.5 


245 


41 


700 


100,000 


69,000 


47.0 


18.0 


235 


40 


800 


97,000 


66,000 


49.5 


19.5 


220 


39 


900 


94,000 


63,000 


52.5 


21.5 


200 


37 


1000 


91,000 


59,500 


55.5 


23.5 


180 


35 


1100 


88,000 


56,000 


58.0 


25.0 


165 


34 


1200 


85,500 


53,000 


60,0 


26.5 


150 


33 


1300 


83,500 


51,000 


61.5 


27.5 


140 


32 


1400 


82,000 


50,000 


62.5 


28.0 


135 


32 



Values are average minimum, except those for hardness, which are average. 



S. A. E. SPECIFICATIONS 



153 



PHYSICAL CHARACTERISTICS OF HEAT TREATED- S. A. E. STEEL NO.J045. 



z 

80 o 160 
</> 

1575 £150 

tto g 

^2:65^ 130 
22 o 
5£6O</>120 

= 9 
#255^110 

Qoe»50ol00 

UjO — 

o™ 1 

WZ35-J 



400 500 600 



DEGREES-FAHRENHEIT 
700 800 900 1000 



1100 1200 1300 



o— ' 

y§3o£ 

op < 

ui320x 
ocuj 5 

?f-15z 

XZ UJ 

°- 5d 
to 

0?. 



90 
80 
70 
60 
50 
40 
30 
20 
10 









































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T. 


S. 






















































































































































R. 


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s!" 


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E, 


H. 

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T. 








































































































Ht 


R. 


A._ 






























S. 


































Mi 


H. 


































lT 




































E. 




































.-Oi 


>re 




































E. 














































































-E4 


0* 


K5- 




























































B 


H, 











































































































































































































205 260 315 



370 425 480 540 
DEGREES- CENTIGRADE 

Heat Treatment 



595 650 705 



800 
750 
700 
650 <£ 
600 1> 
550 z 
500$ 

450 9 

< 

400 x 

_i 

350 < 
oo 

300 g 
250 =j 
200 1 

CO 

150 
100 

50 




The accompanying data apnly to y 2 in. to 1% in. round specimens 
which were heated from 15 to 30 min. at 1490° to 1510° Fahr. ; 
quenched in oil; reheated for 30 min. at temperatures indicated by the 
abscissae of the curves; and finally cooled in air. (Heat Treat- 
ment H.) 

TABULATION OF VALUES PLOTTED IN CURVE 



Reheating 


Tensile 


Elastic 


Reduc- 


Elonga- 




Sclero- 


Tempera- 


Strength, 


Limit, 


tion^ 


tion 


Brinell 


scope 


ture, 


Lb. per 


Lb. per 


Area, 


in 2 In., 


Hard- 


Hard- 


Deg. F. 


Sq. In. 
125,000 


Sq. In. 
90,000 


per Cent. 
35.0 


per Cent. 
12.5 


ness 
300 


ness 


400 


45 


500 


123,500 


88,000 


36.0 


13.0 


290 


45 


600 


121,000 


85,500 


37.0 


13.5 


280 


44 


700 


118,000 


82,500 


39.0 


14.5 


265 


43 


800 


114,000 


79,000 


42.0 


16.0 


250 


41 


900 


110,000 


75,000 


45.0 


17.5 


230 


40 


1000 


106,000 


71,000 


48.0 


19.0 


210 


38 


1100 


102,000 


67,000 


50.5 


20.5 


195 


37 


1200 


99,000 


63,500 


53.0 


21.5 


180 


36 


1300 


96,500 


61,500 


54.0 


22.0 


165 


35 


1400 


95,000 


60,000 


55.0 


22.5 


160 


35 



Values are average minimum, except those for hardness, which are average. 



INDEX 



INDEX 



k BRASIVE resistance of 
steel affected by nickel, 21 
Alloys, hardening tempera- 
tures, 78 
influence on carbon penetra- 
tion, 58 
Alloy steel, classification, 13 
American Society for Testing 
Materials, annealing tem- 
peratures, 33 
Anneal for relieving strains, 30 
Annealed ingot steel, 27 
Annealing, 87 
effect of, 30 
heat, 33 

temperatures, American So- 
ciety for Testing Ma- 
terials, 33 
Area, reduction of, 39 

sectional, steel bar, 37 
Armor plate, steel, affected by 

chromium, 22 
Arrest of temperature, 80 
Atmosphere, non-oxidizing, for 

annealing, 31 
Austenite, 76, 79, 80 

formation of Ferrite and 

Pearlite, 7 
overheating, 52 
properties of, 6 
Axial forces or stresses, 37 
Axles, heat treatment of steel 
for, 135, 141 



B 



ALL bearing cups, heat 
treatment of steel for, 143 



Ball bearings, nickel steel, car- 
burized and heat treated, 
21 
Bar, steel, 36 

Barium Chloride used for heat- 
ing, 93 
Bath furnaces, 76 
Beam, dropping of, 40 
Bearings, ball and roller, nickel 

steel, 21 
Blow-holes in steel, 23 
in steel, affected by silicon, 
20 
Blower Pipes to preheat air, 82 
Bone in carburizing, 67 

rich in hydro-carbons, 72 
Boxes, style of, 97 
Box pouring of steel, 24 
Brine water as quenching me- 
dium, 91 
Brinell Hardness Number 46 

test, 42 
Brittleness, free Cementite, 73 
carburizing steel, affected by 

nickel, 21 
of case, coarse crystalliza- 
tion, 69 
of steel, affected by carbon, 

17 
of steel, affected by man- 
ganese, 18 
of steel, affected by phos- 
phorus, 19 
relieved by drawing, 80 
Bubbles, vapor, 79 



158 



INDEX 



CALCIUM CHLORIDE and 
Sodium Chloride for heat- 
ing, 94 
and Soda Ash mixture as- 
sists in hardening, 94 
Calibration of pyrometer, 101 
Cam rollers, treatment of steel 

for, 125 
Carbide, free, 3 

Carbon content affected by 
oxygen, 34 
affecting depth of case, 56 
governs hardness, 78 
hardening temperatures, 78 
regulates color, 81 
Carbon, effect in steel, 17 
in cast iron, 1 
influence on critical point of 

steel, 14 
influence of, in iron, 3 
influence of thermal points, 9 
influencing silicon, 20 
in steel, 1 
in wrought iron, 1 
monoxide, 67 
monoxide gas in annealing, 

31 
penetration, in carburizing, 58 
steel, classification, 13 
steels, normalizing tempera- 
tures, 15 
Carburizer, density of, 69 
penetration, 69 
value of, 72 
Carburizers, high in thermal 
conductivity lacking hydro- 
carbons, 72 
poorly mixed, 73 
Carburizing, above critical 
range coarsens grain struc- 
ture, 75 
temperature, 58 
material, 66 

materials, internal combus- 
tion, 68 
steels, composition of, 55, 56 
Case, brittleness, 69 
chipping, 69 



Case, depth affected by carbon, 
56 
fine crystalline, double quench- 
ing, 74 
graduation, double quench- 
ing, 74 
hardening, 66 
hardening furnace, 82 
refinement of, 78 
Cementite, 3 
brittleness, 73 
cracks, 73 
globular, 31, 54 
Centigrade equivalent in Fahr., 
105 
vs. Fahrenheit, 104 
Charcoal for carburizing, 67 
Chipping of case, coarse cry- 
stallization, 69 
Chrome steel, annealing, 32 
Chromium in alloy steel, 13 
in steel, carburizing, 57 
in steel, effect of, 22 
retards transformation rate, 
76 
Classification of steel, 13 
Coal as fuel, 89 
Coarse crystalline formation, 29 

structure, 26 
Coarse crystallization, combus- 
tion in pot, 69 
above critical range, 30 
of case, 69 
Coarse grain, prolonged heat- 
ing at high carburizing 
temperatures, 75 
Coke for carburizing, 67 
Cold shortness, phosphorus in 

steel, 19 
Color, carbon content, 81 
Combustion in pot, 69 
internal, carburizing mate- 
rials, 68 
Composition, of steel, 1 
of pots, 99 

of steel, refining tempera- 
tures, 74 
of steels for carburizing, 56 



INDEX 



159 



Compressive forces, 37 
Conductivity, carburizing mate- 
rial, 67 
thermal of carburizing mate- 
rials, 68 
Connecting rods, vanadium 

steel for, 23 
Continual heat, expansion and 
contraction, 89 
heat proves economical, 89 
Contraction and expansion, 

continual heat, 89 
Cooling dependent on kind of 
quenching medium, 78 
crystal growth, 26 
dependent on size of piece of 

steel, 78 
speed of quenching liquid, 90 
Copper plating to prevent car- 

burization, 95 
Core, brittleness, in carburizing 
steel, affected by nickel, 21 
tough, double quenching in, 
74 
Cracking or warping, 79 
in high carbon steels, 23 
in steel, caused by sulphur, 19 
prevented, 77 
Cracks, free Cementite in 

quantity, 73 
Crank pins, vanadium steel for, 

23 
Crank shafts, chromium steel 
for, 22 
heat treatment of steel for, 

129 135, 141 
vanadium steel for, 23 
Critical point, low carbon steel, 

' , 14 

high carbon steel, 15 

of steel, affected by nickel, 

. . 21 
Critical points, medium carbon 

steel, 14 

of steel, 7 
Critical range, annealing, 30 

of steel, grain size, 26 
Cropping — steel ingots, 23 



Cross sections, hardening of, 
79 

Crystal growth, cooling, 26 

Crystalline growth in steel, af- 
fected by chromium, 22 

Crystallization, coarse, 69 
alloy steels, 63 

Cyanide bath, 66 

Cyanide solution prevents lead 
sticking to work, 93 

Cyanogen, 67 

■pvECALESCENCE, of steel, 

Decarbonizing of carbon steel 

in annealing, 33 
Decarburization, 72 
Density of carburizing mate- 
rial, transmission, heat, 69 
of steel, affected by mechan- 
ical working, 26 
Depth of penetration in carbur- 
izing, 61 
carburizing temperature, 60 
Distortion, 77 

Drawing for colors in open 
furnace, 81 
operation, 81 
relieves brittleness, 80 
relieves hardness, 80 
Drawing temperature, ductility, 
80 
softness, 80 
Drive shafts, heat treatment of 

steel for, 141 
Driving shafts, heat treatment 

of steel for, 129, 135 
Drop forgings, heat treatment 

of steel for, 126 
Dropping of the beam, 40 
Ductility of steel, affected by 
manganese, 18 
affected by phosphorus, 19 
affected by nickel, 21 
in annealing, 30 
reduction of area, 40 



160 



INDEX 



Ductility regulated by drawing 
temperature, 80 

ELASTIC limit, 36, 39 
of steel, affected by chro- 
mium, 22 
of steel, affected by nickel, 
21 
Electricity as fuel, 89 
Elements in steel, effect of, 17 
Elongation, 36 
ductility, 40 
steel bar, 37 
Eutectic case, carburized steel, 

65 . 
Eutectoid, 3 

Eutectoid steel, classification, 13 
critical temperature, 12 
critical point, 15 

Excess Cementite, 5 

Expansion and contraction con- 
tinual heat, 89 

FAHRENHEIT vs. Centi- 
grade, 104 
vs. Reaumer, 104 
Ferrite and Cementite, 3 
in steel, 1 
pure iron, 3 
Ferrite and Pearlite, magnet- 
ism of, 6 
conversion to Austenite, 7 
Fire clay detrimental to carbur- 

izing material, 101 
Flame, neutral, for heating, 88 
Forging quality of steel af- 
fected by chromium and 
nickel, 23 
strains, liberation of, 79 
"Freckled Corners," 73 
Free Cementite, high tempera- 
ture or carburizing mate- 
rial, 73 
Fuel, 89 

Furnace, case hardening, 82 
construction of, 82 
operation of, 84 



Furnace, open-fired type, 76 
Furnaces, bath, 76 

small, preferable, 82 

position of, 87 

preheating, 76 

GAS for carburizing, 66 
as fuel, 89 
Gaseous vapors, prevention, 79 
Gases, carburizing, 67 
Gears, chrome nickel steel, 22 
drawing temperature, 148 
heat treatment of steel for, 

139 
nickel steel, 21 
treatment of steel for, 125 
Vanadium steel for, 23 
Globular Cementite, 31 
Globular Pearlite in annealing, 

31 
Grain, low carbon forging steel, 

27 . 
refining, in chrome steels, 33 

Grain size, in annealing, 34 

of steel,. 25 
Grain structure, carburizing 
above critical range, 75 
of steel, affected by chrom- 
ium, 22 
Gun barrels, vanadium steel 
for, 23 ' 

HADFIELD, R. A., dis- 
coverer of manganese, 17 
Handling of hot-boxes, 98 
Hardening bath, construction 
of, 91 
depth, of steel, affected by 

chromium, 22 
of steel, affected by carbon, 

17 
of threaded parts, 96 
properties, of steel, affected 

by annealing, 34 
temperatures dependent on 
carbon content, 78 



INDEX 



161 



Hardness, maximum, 76 
carbon content, 78 
methods of testing, 40 
Brinell test, 42 
Keep's test, 43 
Rockwell test, 45 
Shore's Scleroscope, 42 
Turner's Sclerometer, 41 
of steel, affected by man- 
ganese, 18 
of steel, affected by chrom- 
ium, 22 
relieved by drawing, 80 
value of metals, 45 
Heat, annealing, 33 
critical points of steel, 7 
effect on structure, 26 
range of temperatures, 33 
Heat treatment of steel, 51 
affected by chromium, 22 
nickel steel, 21 
Heat treating temperature, af- 
fected by manganese, 18 
High carbon steels, quenching 
medium, 90 
duty shafting, heat treatment 

of steel for, 142 
temperatures, coarse grain, 75 
Hot shortness, sulphur in steel, 

19 
Hydro-carbons, 72 
in carburizing, 67 

Hypereutectic case, carburized 
steel, 65 

Hypereutectoid, Pearlite and 
Cementite, 5 
steel, classification, 14 

Hypoeutectic case, carburized 

steel, 65 
Hypoeutectoid steel, classifica- 
tion, 14 
critical point, 15 
critical temperature, 12 
Ferrite and Pearlite, 5 

Hysteresis, critical point of 
steel, 12 

12 



TMPURITIES in iron and 
A steel, 1 

in steel, 23 
Ingot, low carbon forging steel, 

26 
Iron carbide in steel, 1 

scale detrimental to carbur- 
izing material, 101 
wrought, 1 



K 



AOLIN prevents carburiza- 
tion, 95 



LAMELLAR PEARLITE 
/in annealing, 31 
Lead bath, disadvantages, 93 

quenching mediums, 93 
Lead pot, cleansing of, 93 
Leather for carburizing, 67 
Liberation of forging strains, 

79 
Low carbon steel, refinement 
of, 77 
thermal critical points, 14 

MACHINE steel, 124 
Machining quality of 
chromium steel, 22 
high carbon steel, 31 
low carbon steels, 32 
Machining quality of steel, af- 
fected by phosphorus and 
sulphur, 20 
Machining qualities of steel, 
carburizing, 57 
affected by manganese, 18 
Magnetism, Austenite, 6 
Ferrite and Pearlite, 6 
Manganese, influenced by sili- 
con, 21 

in straight carbon steels, 13 
retards transformation rate, 

76 
sulphide in steel, effect, of, 19 
Manganese in steel, effect of, 17 
annealing temperature, af- 
fected by, 33 
for carburizing, 57 



162 



INDEX 



Martensite, 6, 53, 76, 79, 80 
retention of, 79 
harder than Austenite, 9 

Martensitic structure, nickel 
steels, 21 

Maximum strength, 36, 39 

Mechanical treatment of steel, 
25 

Metals, hardness value, 45 

Moisture detrimental to car- 
burizing material, 101 

Muffle furnace produces hard- 
est surface, 88 

NEUTRAL flame for heat- 
ing, 88 
prevents scaling, 88 
prevents surface decarburiza- 
tion, 88 
Nickel, effect on machining 
quality of chromium steel, 
22 
in alloy steels, 13 
in steel carburizing, 57 
in steel, effect of, 21 
percentage in steel, 21 
retards transformation rate, 
76 
Nitrogen, affected by vanadium, 

23 
Normalizing chrome steel, 32 
Normalizing steel, 16 

OIL as fuel, 89 
as quenching medium, 9J 
quenchinp- medium for high 

carbon steels, 90 
quenching medium for thin 

pieces, 90 
quenching steel, 32 
Open furnace, colors, 81 
;F i fired furnaces, 76 
hearth steel, 123 
Overheating in carburizing, 68 
Oxidizing gases, surface decar- 

burization, 72 
Oxidation of carbon steel in 
annealing, 34 



Oxygen, affinity of vanadium 
for, 23 

PEARLITE, 3, 79, 80 
and Ferrite, 3 
and Ferrite, conversion to 

Austenite, 7 
globular or lamellar, 31 
laminated, 54 
prevention of, 79 
Penetrating power, carburizing 

materials, 72 
Penetration, chrome steels, 62 

depth of, in carburizing, 61 
Permanent set, steel bar, 39 
Phosphorus in steel, effect of, 
18 
affecting manganese, 18 
carburizing, 56 
in iron and steel, 1 
in straight carbon steels, 13 
Physical properties of oil used 
for quenching, 92 
affected by annealing, 30 
of steel, 36 

of steel, affected by elements, 
17 
Pipes suitable for carburizing 

purposes, 101 
Piping in steel, 23 
Piston rods, vanadium steel 

for, 23 
Pots, style of, 97 

with cored centres, 99 
Preheating furnaces, 76 
Prevention of gaseous vapors, 

79 
Properties of steel, affected by 

elements, 17 
Propeller shafts, heat treatment 

of steel for, 129 
Push rods, heat treatment of 

steel for, 125 
Pyrometer, calibration of, 101 
fire ends, location of, 88 
fire ends, protection, 88 
portable, 88 
Pyrometers, 47, 78 



INDEX 



163 



QUENCH directly from car- 
burizing pot, 75 
Quenching bath, function of, 

80 
bath, water and oil, 92 
case graduation, 74 
crystalline case, 74 
eliminated, in high nickel 

steels, 21 
liquid, cooling speed, 90 
medium, 77 
medium, cooling dependent, 

78 
medium for high carbon 

steels, 90 
medium, temperature, 78 
medium, water, 90 
mediums for work heated in 

lead bath, 93 
method of, 90 
on ascending heat to reduce 

scale, 77 
steel, affected bv chromium, 

22 
tanks regulated by size of 

work, 90 
tough core, 74 
vertical, prevents warping, 77 



R 



APID heating detrimental, 



Range of temperature, critical, 
9 

Reaumer vs. Centigrade, 104 
vs. Fahrenheit, 104 

Recalescence of steel, 9 

Red shortness, manganese sul- 
phide in steel, 20 

Reducing atmosphere prevents 
surface decarburization, 72 

Reduction of area, 36, 39 

Refinement of case, 78 
of low carbon steel, 77 

Refining coarse structure by 
annealing, 35 
temperatures, 74 

Roberts-Austen chart, 10 



Rolled and hammered ingot 
steel, 27 

Roller bearings, nickel steel, 
carburized and heat treated, 
21 

Rupture caused by uneven heat- 
ing, 77 

SALT bath, 52 
Saws, vanadium steel for, 
23 
Scale, prevention in annealing, 

33 
Scaling, prevention, 88 
Sclerometer, Turner's, 41 
Scleroscope, Shore's, 42 
Sectional area, steel bar, 37 
Segregation of elements, 23 
Shafts, nickel steel, carburized 

and heat treated, 21 
Shock resisting qualities of 
steel, affected by chro- 
mium, 22 
resistance of steel, affected 

by nickel, 21 
resisting quality of steel, af- 
fected by phosphorus, 18 
resisting quality of steel, af- 
fected by vanadium, 23 
Shore's Scleroscope, 42 
Shortening, steel bar, 37 
Silicon, in iron and steel, 1 
in steel, carburizing, 57 
in steel, effect of, 20 
in straight carbon steels, 13 
Size regulates time of drawing, 

81 
Slag, freedom of steel from, 1 

in steel, 23 
Slip bands in steel, 34 
Sodium Chloride for heating, 

94 
Softness of steel in annealing, 
30 
regulated by drawing tem- 
perature, 80 
Sorbite, 9, 76, 80 



164 



INDEX 



Soundness of steel, affected by 

silicon, 20 
Specimen, carburized steel, pre- 
paring, 65 
Springs, drawing temperature, 
148 

heat treatment of, 129 

vanadium steel for, 23 
Steel, affected by chromium, 22 

annealing, 30 

austenite stage, 76 

carburizing, affected by 
nickel, 21 

carburizing, composition of, 
56 

classification of, 13 

composition of, 1 

effect of nickel, 21 

effect of vanadium in, 23 

elements, effect of, 17 

martensite form, 76 

mechanical treatment of, 25 

physical properties of, 36 

tensile strength affected by 
carbon, 17 

thermal critical points of, 13 

thermal or heat treatment, 51 
Steering wheel pivot pins, 
treatment of steel for, 125 
Strain anneal, 31 
Strength, maximum, 39 

of steel, affected by man- 
ganese, 18 

in steel, affected by nickel, 21 

tensile of steel, affected by 
carbon, 17 
Stress, unit, 37 

axial, 37 

compressive, 37 

in steel, 36 

resistance, alternate in steel, 
affected by chromium, 22 

tensile, 37 

vibrational, resisting qualities 
of steel affected by phos- 
phorus, 19 
Structural change, annealing, 
30 



Structural changes in heat 
treatment, 52 
grain in steel, affected by 

chromium, 22 
steel, heat treatment of, 127 
Sulphur, effect in steel, 19 
in steel, affecting mangenese, 

18 
in steel, carburizing, 57 
in straight carbon steel, 13 
Surface decarburization, pre- 
vention of, 88 

TEMPERATURE affected 
by manganese, 18 
arrest, 80 
carburizing, 58 
carburizing control of, 68 
effect in carburizing, 67 
in pot higher than indicated 

by instruments, 67 
of quenching medium, 78 
refining composition of steel, 
74 
Temperatures, annealing, 
American Society for Test- 
ing Materials, 33 
Tempering heats of steel, 103 
Tensile forces, 37 
strength of steel, 36 
strength of steel, affected by 

carbon, 17 
strength of steel, affected by 

nickel, 21 
test, 40 
Tension, 37 
Test, hardness, 40 
Brinell, 42 
Keep's, 43 
Rockwell, 45 
Shore's Scleroscope, 42 
Turner's Sclerometer, 41 
tensile, 40 
Thermal changes of steel, 7 
Threaded parts, hardening, 96 
Time of drawing regulated by 

size of pieces, 81 
Tools — Quenching of, 78 



INDEX 



165 



Toughness of steel, affected by 
manganese, 18 
of steel, affected bv nickel, 

21 
of steel, affected by silicon, 

20 
steel gears, of chrome nickel 
steel, 22 
Transformation of steel, 7 

rate retarded, 76 
Transmission shafts, heat treat- 
ment of steel for, 135, 141 
mechanical, of steel, 25 
Troostite, 76, 80 
Turner's Sclerometer, 41 

UNDERFIRED carburizing 
furnaces unsatisfactory, 84 
Uneven heating cause of dis- 
tortion, 77 
penetration, poorly mixed 
carburizers, 73 
Unit stress, 37 



VALUE of carburizer, kind 
of gases, 72 
Vanadium, effect on machining 
quality of chromium steel, 
22 

in alloy steels, 13 
in steel carburizing, 57 
in steel, effect of, 23 
Vapor bubbles, 79 
Vapors, prevention, 79 

WARPING, cause of, 94 
or cracking, 79 
prevented, 77 
Water and oil used as a 
quenching bath, 92 
as quenching medium, 91 
glass prevents carburization, 

95 
quenching medium for steel 
below 90 point, 90 
Weak carburizer, decarburiza- 
tion, 72 



-WITH RECOMMENDED HEAT TREATMENTS 



Ci 



3t 



Heat Treatment A 
fter forging or machining : 
, Carbonize between 1600° P. 
and 1750° F. (1650° -1750° 
F. desired.) 
Cool slowly or quench. 
Reheat to 1450° -1500° F. 
and quench. 

Heat Treatment B *■ 

g c fter forging or machining: 

Carbonize between 1600° F. 
and 1750° F. (1650° -1700° 
F. desired.) 

Cool slowly in the carboniz- 
ing mixture. 

Rebeat to 1550° -1025° F. 
Ni Quench. 

I Rebeat to 1400°-1450° F. 

Quencb. 

Draw in hot oil at 300° to 
450° F., depending upon 
tbe degree of hardness de- 
sired. 

Heat Treatment D 
\ev forging or machining: 

eat to 1500° -1600° F. 
iuench. 

ieheat to 1450°-1500° F. 
Juench. 
leheat to 600°-1200° F. and 

cool slowly. 

Heat Treatment B 
sr forging or machining: 

[eat to 1500° -1550° F. 

ool slowly. 

.eheat to 1450°-1550° F. 

Iuench. 

eheat to 600° -1200° F. and 

pool slowly. 

Heat Treatment F 
r shaping or coiling: 

^at to 1425° -1475° F. 

'lench in oil. 

$heat to 400° -900° F., In 
ccordance with temper 
lesired, and cool slowly. 



Heat Treatment G 
A forging or machining : 
l.|rbonize between 1600° F. 
d 1750° F. (1650° -1700° 

. desired.) 
2.bl slowly in the carbon- 

ing mixture. 

3. bent to 1500°-1550° F. 

4. lench. 



Ch 



HEAT TREATMENTS 



5. Reheat to 1300° -1400° F. 

6. Quench. 

7. Reheat to 250° -500° F. (in 

accordance with the neces- 
sities of the case) and cool 
slowly. 

Heat Treatment H 
After forging or machining: 

1. Heat to 1500°-1600° F. 

2. Quench. 

3. Rebeat to 600° -1200° F. and 

cool slowly. 

Heat Treatment K 
After forging or machining : 

1. Heat to 1500° -1550° F. 

2. Quench. 

3. Rebeat to 1300° -1400° F. 

4. Quench. 

5. Rebeat to 600° -1200° F. and 

cool slowly. 

Heat Treatment L 
After forging or machining: 

1. Carbonize between 1600° F. 

and 1750° F. (1650° -1700° 
F. desired). 

2. Cool slowly in the carboniz- 

ing mixture. 

3. Rebeat to 1400° -1500° F. 

4. Quench. 

5. Reheat to 1300°-1400° F. 

6. Quench. 

7. Reheat to 250°-500° F. and 

cool slowly. 

Heat Treatment M 
After forging or machining: 

1. Heat to 1450° -1500° F. 

2. Quench. 

3. Reheat to 500° -1250° F. and 

cool slowly. 

Heat Treatment P 
After forging or machining: 

1. Heat to 1450° -1500° F. 

2. Quench. 

3. Reheat to 1375° -1450° F. 

4. Quench. 

5. Reheat to 500°-1250° F. and 

cool slowly. 

Heat Treatment Q 

After forging : 

1. Heat to 1475° -1525° F. (Hold 
at this temperature one- 
half hour, to insure thor- 
ough heating). 



2. Cool slowly. 

3. Machine. 

4. Reheat to 1375° -1425° F. 

5. Quench. 

6. Reheat to 250° -550° F. and 

cool slowly. 

Heat Treatment B 
After forging : 

1. Heat to 1500° -1550° F. 

2. Quench in oil. 

3. Reheat to 1200°-1300° F. 

(Hold at this temperature 
three hours.) 

4. Cool slowly. 

5. Machine. 

6. Reheat to 1350° -1450° F. 

7. Quench in oil. 

8. Reheat to 250° -500° F. and 

cool slowly. 

Heat Treatment 8 
After forging or machining: 

1. Carbonize at a temperature 

between 1600° F. and 1750° 
F. (1650° -1700° F. de- 
sired). 

2. Cool slowly in the carboniz- 

ing mixture. 

3. Reheat to 1650° -1750° F. 

4. Quench. 

5. Rebeat to 1475° -1550° F. 

6. Quench. 

7. Reheat to 250° -550° F. and 

cool slowly. 

Heat Treatment T 
After forging or machining: 

1. Heat to 1650° -1750° F. 

2. Quench. 

3. Reheat to 500° -1300° F. and 

cool slowly. 

Heat Treatment IT 
After forging : 

1. Heat to 1525°-1600° F. (Hold 

for about one-half hour.) 

2. Cool slowly. 

3. Machine. 

4. Reheat to 1650° -1700° F. 

5. Quench. 

6. Reheat to 350°-550° F. and 

cool slowly. 

Heat Treatment V 
After forging or machining: 

1. Heat to 1650° -1750° F. 

2. Quench. 

3. Reheat to 400° -1200° F. and 

cool slowly. 



VJ 



tilicc 5 per cent, to .50 per cent. 



CHART OF STEEL SPECIFICATIONS- AMERICAN SOCIETY OF AUTOMOTIVE ENGINEER S- WITH RECOMMENDED HEAT TREATMENTS 



Nickxl Steels.. 



Chbouiuw Steels.. 



Chromium Vanadium Steels 



.30 to .-10 
.a-> to .ir. 
40 to .50 



.55 1> 



.20 to 
.20 to 


45 
45 


!i 


.20 to 


45 


.a 


.50 toO 
.50 to 
.SOU 


80 
80 
SO 


0. 

! 


.50 to 

.50 to 
.50 to 


80 

80 
80 




.50 to 
.20 to 


80 
45 


. 


3.00 to 


80 
70 


0. 



* Another grade of this type of ateel is available will chromium content of .15 per a 
t Two types of steel are available to this class; one with manganese .25 per cent. t< 
J Not specified and ia not to be included in specif ication when ordering steel. 
5 Steel made by the acid process may contain maximum .05 phosphorus. 
|| Heat Treatment "M" is used when this steal is intended for structural parts. 
H Heat Treatment "T" is used when this steel is intended for structural parts. 



.i-ii...l 


75 


3 


.2510:1 


76 


3. 


.25 to 3 


75 


3. 


.2.5 t.,:i 


75 


3 


.25 to 3 


75 


3- 


.00 to I 


50 




.111110 1 


fill 




.OOtol 


oil 




.OOtol 


50 




HO 10 1 


50 
00 




.50 to 2 


01) 




..'.II to 2 


llll 




.50 to 2 


00 




.75to3 


25 


3 


.75 1.13 


25 


a. 


.75 to 3 


25 


3. 


.25 to 3 


75 


3 


25 to 3 


75 


3 


.25 to 3 


75 


3. 



:45to 
.45 to 


0.75 - 
.75- 





.45 to 
.45 to 
.00 to 


>5* 
1.25 


1 


.90 to 
.90 to 
.90 to 


1.25 
1.25 
1.25 


1 
1 
1. 


.goto 

.60 to 


MS 
.95 




.25 to 
.25 to 


1.75 
1.7.5 
1 75 


1 


.05 to 
.65 to 
.65 to 


0.85 
.85 
.85 





.90to 
.90 to 


1.10 

1 in 
1.30 


1 


.10 to 


1.30 


1 


).80 to 
.80 to 
.80 to 


1 ID 
1.10 
1.10 





.80 to 
.80 to 
.80 to 


1.10 
1.10 
1.10 




.80 to 
.80 to 


1.10 





p .45 per cent. It has somewhat lower physical properties. 



Beat Treatment A 
After forging or machining: 
L Carbonize between HiflO p. 
nod 17r,0° F. UD.'.U -17,-rO-' 



Beat Treatment B 
After forging or machining: 

1. Cnrbonfie between ltioo 6 f 

and 1750" P. ( ur.o lino' 
F. desired.) 

2. C'Dul slowly in Mil- f!i [-lioniz- 

ing mixture. 

X Iteheat lo l,w0°-1025° F. 

4. Quench. 

.".. [(cheat to 14u0°-14G0° F. 

0. Quench. 

7. Draw In hot oil at 300° to 
450° P., depending upon 
the degree of hardness de- 
feat Treatment D 

After forging or machining: 

i Quench. 

. Reheat t 

. Quench. 

0. Heheat t 

cool slowly. 

Heat Treatment B 
After forging or machining: 

1. Heat to 1GOO°-1550° P. 

2. fool slowly. 

3. Reheat to 1450°-ir>50° P. 



Heat to l.j00°-ir,00° P. 
Quench. 
3. Reheat to 1450°-1500° F 

> 00O°-12OO° P. 



Helical 



slowly. 

Beat Treatment F 
After shaping or colling: 
1. Heat to 1425«-147k! Ii 

ench li 



3. Hche; 



After forging or machining: 

1. Carbonize between 1(100° P. 

and 17o0° P. \U):t}< -lTnir 



1500° -1550° F. 



,50 per cent, (.35 per c 



■ .20 per cent.; the other with manganese .50 per c 



■. do.-irct!,) iriJ "ilii'Li ].j 1 



HEAT TREATMENTS 



1. Heat to 1500°.1GOO° 

2. Quench. 

3. Uelieat to ll0il°-1200 o F mid 



5. Reheat to 1300°. 1400* P. 
fl. Quench. 

7. Reheat to 2:,u".r,m 

BUito v 

Blowly, 
Beat Treatment B 
After forging or machining 

2! Quench 
Iteheat ™ .,• 
cool slowly. 

Heat Treatment K 
After forging or machining: 

1. Heat to lo00°-ir>D0° P. 

2. Quench. 

'■'-. Ifeheal to 1300° -HOO F 
•1. Quench, 

5, Iteheat to 6410° -1200° P. (in 
cool Blowly. 

Heat Treatment L 
After forging or machining: 



•sYrerh 
low 

lllL' ]!ll> 



hetv 



'-1200° P. and 2. Quench 



2. Cool Blowly 'in the enrbo: 
llsture. 
to 1400<M50u° P. 

:..' Reheat to 1300°-14O0° F. 

6. Quench. 

7. Heheat to 2. r >0 o -500° F. am 

cool Blowly. 

Heat Treatment M 
After forging or machining: 
1. Heat to 1450° -1500* P. 



400°-*100° F.. in 2. Quench 



Heat Treatment P 
After forging or machining: 
1. Heat to 1460O-.1500 F. 



1375 o -1450" F. 
5OO°-1250° F. and 



cool slowly, 
Heat Treatment Q 



2. Cool slowly. 

5. Machine. 

4. Reheat to 1375*- 1423° F 
B. Quench. 

6. Iteheat to 250°-550° F. 

cool alowly. 

Beat Treatment R 
After forging: 



. Heat to 
. Que 



-1500° P. 

liWMSOO 



(Hold aV'th'la"temp 
Cool 

■:■ 

1350°-1450° 
250° -600° P 



.".. Ma.'hln 
fl. Iteheat 
7. Oneneh 



nud 



Beat Treatment 3 
After forging or machlnlnK: 

between mni' l' "a't,]' 1 ;'!u'' 
P. (l(lo0 o -1700° F. de- 

2. Cool slowly In the cnrbonU- 

3. Heheat to 1030" -1760° P. 



.. Que.. 
.1. Kehe 



) 147 



6. Que 

7. Iteheat to 250°-fl60° F. am 

cool slowly. 

Beat Treatment T 
After forging or machining: 
2! Quench. 



Beat Treatment U 
After forging : 



Meat lo lo2."i°-10()0 P. (Hold 

for ale. nt one- half hour.) 
Cool slowly. 
Machine. 
Iteheat to loo0°-1700 o P. 



a. Marhin 
4. Iteheat 
fi. (>neiieb 



Beat Treatment V 
After forging or machining 



1 insure thor- 3. Reheat' 1 



I 



